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Diffstat (limited to 'man5')
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diff --git a/man5/acct.5 b/man5/acct.5 new file mode 100644 index 0000000..e1d88d4 --- /dev/null +++ b/man5/acct.5 @@ -0,0 +1,161 @@ +.\" Copyright (C) 2008, Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH acct 5 2023-05-03 "Linux man-pages 6.05.01" +.SH NAME +acct \- process accounting file +.SH SYNOPSIS +.nf +.B #include <sys/acct.h> +.fi +.SH DESCRIPTION +If the kernel is built with the process accounting option enabled +.RB ( CONFIG_BSD_PROCESS_ACCT ), +then calling +.BR acct (2) +starts process accounting, for example: +.PP +.in +4n +acct("/var/log/pacct"); +.in +.PP +When process accounting is enabled, the kernel writes a record +to the accounting file as each process on the system terminates. +This record contains information about the terminated process, +and is defined in +.I <sys/acct.h> +as follows: +.PP +.in +4n +.EX +#define ACCT_COMM 16 +\& +typedef u_int16_t comp_t; +\& +struct acct { + char ac_flag; /* Accounting flags */ + u_int16_t ac_uid; /* Accounting user ID */ + u_int16_t ac_gid; /* Accounting group ID */ + u_int16_t ac_tty; /* Controlling terminal */ + u_int32_t ac_btime; /* Process creation time + (seconds since the Epoch) */ + comp_t ac_utime; /* User CPU time */ + comp_t ac_stime; /* System CPU time */ + comp_t ac_etime; /* Elapsed time */ + comp_t ac_mem; /* Average memory usage (kB) */ + comp_t ac_io; /* Characters transferred (unused) */ + comp_t ac_rw; /* Blocks read or written (unused) */ + comp_t ac_minflt; /* Minor page faults */ + comp_t ac_majflt; /* Major page faults */ + comp_t ac_swaps; /* Number of swaps (unused) */ + u_int32_t ac_exitcode; /* Process termination status + (see wait(2)) */ + char ac_comm[ACCT_COMM+1]; + /* Command name (basename of last + executed command; null\-terminated) */ + char ac_pad[\fIX\fP]; /* padding bytes */ +}; +\& +enum { /* Bits that may be set in ac_flag field */ + AFORK = 0x01, /* Has executed fork, but no exec */ + ASU = 0x02, /* Used superuser privileges */ + ACORE = 0x08, /* Dumped core */ + AXSIG = 0x10 /* Killed by a signal */ +}; +.EE +.in +.PP +The +.I comp_t +data type is a floating-point value consisting of a 3-bit, base-8 exponent, +and a 13-bit mantissa. +A value, +.IR c , +of this type can be converted to a (long) integer as follows: +.PP +.nf + v = (c & 0x1fff) << (((c >> 13) & 0x7) * 3); +.fi +.PP +The +.IR ac_utime , +.IR ac_stime , +and +.I ac_etime +fields measure time in "clock ticks"; divide these values by +.I sysconf(_SC_CLK_TCK) +to convert them to seconds. +.SS Version 3 accounting file format +Since Linux 2.6.8, +an optional alternative version of the accounting file can be produced +if the +.B CONFIG_BSD_PROCESS_ACCT_V3 +option is set when building the kernel. +With this option is set, +the records written to the accounting file contain additional fields, +and the width of +.I c_uid +and +.I ac_gid +fields is widened from 16 to 32 bits +(in line with the increased size of UID and GIDs in Linux 2.4 and later). +The records are defined as follows: +.PP +.in +4n +.EX +struct acct_v3 { + char ac_flag; /* Flags */ + char ac_version; /* Always set to ACCT_VERSION (3) */ + u_int16_t ac_tty; /* Controlling terminal */ + u_int32_t ac_exitcode; /* Process termination status */ + u_int32_t ac_uid; /* Real user ID */ + u_int32_t ac_gid; /* Real group ID */ + u_int32_t ac_pid; /* Process ID */ + u_int32_t ac_ppid; /* Parent process ID */ + u_int32_t ac_btime; /* Process creation time */ + float ac_etime; /* Elapsed time */ + comp_t ac_utime; /* User CPU time */ + comp_t ac_stime; /* System time */ + comp_t ac_mem; /* Average memory usage (kB) */ + comp_t ac_io; /* Characters transferred (unused) */ + comp_t ac_rw; /* Blocks read or written + (unused) */ + comp_t ac_minflt; /* Minor page faults */ + comp_t ac_majflt; /* Major page faults */ + comp_t ac_swaps; /* Number of swaps (unused) */ + char ac_comm[ACCT_COMM]; /* Command name */ +}; +.EE +.in +.SH VERSIONS +Although it is present on most systems, it is not standardized, +and the details vary somewhat between systems. +.SH STANDARDS +None. +.SH HISTORY +glibc 2.6. +.PP +Process accounting originated on BSD. +.SH NOTES +Records in the accounting file are ordered by termination time of +the process. +.PP +Up to and including Linux 2.6.9, +a separate accounting record is written for each thread created using +the NPTL threading library; +since Linux 2.6.10, +a single accounting record is written for the entire process +on termination of the last thread in the process. +.PP +The +.I /proc/sys/kernel/acct +file, described in +.BR proc (5), +defines settings that control the behavior of process accounting +when disk space runs low. +.SH SEE ALSO +.BR lastcomm (1), +.BR acct (2), +.BR accton (8), +.BR sa (8) diff --git a/man5/charmap.5 b/man5/charmap.5 new file mode 100644 index 0000000..280ba4e --- /dev/null +++ b/man5/charmap.5 @@ -0,0 +1,105 @@ +.\" Copyright (C) 1994 Jochen Hein (Hein@Student.TU-Clausthal.de) +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.TH charmap 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +charmap \- character set description file +.SH DESCRIPTION +A character set description (charmap) defines all available characters +and their encodings in a character set. +.BR localedef (1) +can use charmaps to create locale variants for different character sets. +.SS Syntax +The charmap file starts with a header that may consist of the +following keywords: +.TP +.RI < code_set_name > +is followed by the name of the character map. +.TP +.RI < comment_char > +is followed by a character that will be used as the comment character +for the rest of the file. +It defaults to the number sign (#). +.TP +.RI < escape_char > +is followed by a character that should be used as the escape character +for the rest of the file to mark characters that should be interpreted +in a special way. +It defaults to the backslash (\e). +.TP +.RI < mb_cur_max > +is followed by the maximum number of bytes for a character. +The default value is 1. +.TP +.RI < mb_cur_min > +is followed by the minimum number of bytes for a character. +This value must be less than or equal than +.RI < mb_cur_max >. +If not specified, it defaults to +.RI < mb_cur_max >. +.PP +The character set definition section starts with the keyword +.I CHARMAP +in the first column. +.PP +The following lines may have one of the two following forms to +define the character set: +.TP +.RI < character >\ byte-sequence\ comment +This form defines exactly one character and its byte sequence, +.I comment +being optional. +.TP +.RI < character >..< character >\ byte-sequence\ comment +This form defines a character range and its byte sequence, +.I comment +being optional. +.PP +The character set definition section ends with the string +.IR "END CHARMAP" . +.PP +The character set definition section may optionally be followed by a +section to define widths of characters. +.PP +The +.I WIDTH_DEFAULT +keyword can be used to define the default width for all characters +not explicitly listed. +The default character width is 1. +.PP +The width section for individual characters starts with the keyword +.I WIDTH +in the first column. +.PP +The following lines may have one of the two following forms to +define the widths of the characters: +.TP +.RI < character >\ width +This form defines the width of exactly one character. +.TP +.RI < character >...< character >\ width +This form defines the width for all the characters in the range. +.PP +The width definition section ends with the string +.IR "END WIDTH" . +.SH FILES +.TP +.I /usr/share/i18n/charmaps +Usual default character map path. +.SH STANDARDS +POSIX.2. +.SH EXAMPLES +The Euro sign is defined as follows in the +.I UTF\-8 +charmap: +.PP +.nf +<U20AC> /xe2/x82/xac EURO SIGN +.fi +.SH SEE ALSO +.BR iconv (1), +.BR locale (1), +.BR localedef (1), +.BR locale (5), +.BR charsets (7) diff --git a/man5/core.5 b/man5/core.5 new file mode 100644 index 0000000..c19846e --- /dev/null +++ b/man5/core.5 @@ -0,0 +1,684 @@ +.\" Copyright (c) 2006, 2008 by Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH core 5 2023-05-03 "Linux man-pages 6.05.01" +.SH NAME +core \- core dump file +.SH DESCRIPTION +The default action of certain signals is to cause a process to terminate +and produce a +.IR "core dump file" , +a file containing an image of the process's memory at +the time of termination. +This image can be used in a debugger (e.g., +.BR gdb (1)) +to inspect the state of the program at the time that it terminated. +A list of the signals which cause a process to dump core can be found in +.BR signal (7). +.PP +A process can set its soft +.B RLIMIT_CORE +resource limit to place an upper limit on the size of the core dump file +that will be produced if it receives a "core dump" signal; see +.BR getrlimit (2) +for details. +.PP +There are various circumstances in which a core dump file is +not produced: +.IP \[bu] 3 +The process does not have permission to write the core file. +(By default, the core file is called +.I core +or +.IR core.pid , +where +.I pid +is the ID of the process that dumped core, +and is created in the current working directory. +See below for details on naming.) +Writing the core file fails if the directory in which +it is to be created is not writable, +or if a file with the same name exists and +is not writable +or is not a regular file +(e.g., it is a directory or a symbolic link). +.IP \[bu] +A (writable, regular) file with the same name as would be used for the +core dump already exists, but there is more than one hard link to that +file. +.IP \[bu] +The filesystem where the core dump file would be created is full; +or has run out of inodes; or is mounted read-only; +or the user has reached their quota for the filesystem. +.IP \[bu] +The directory in which the core dump file is to be created does +not exist. +.IP \[bu] +The +.B RLIMIT_CORE +(core file size) or +.B RLIMIT_FSIZE +(file size) resource limits for the process are set to zero; see +.BR getrlimit (2) +and the documentation of the shell's +.I ulimit +command +.RI ( limit +in +.BR csh (1)). +However, +.B RLIMIT_CORE +will be ignored if the system is configured to pipe core dumps to a program. +.IP \[bu] +The binary being executed by the process does not have read +permission enabled. +(This is a security measure to +ensure that an executable whose contents are not readable +does not produce a\[em]possibly readable\[em]core dump containing +an image of the executable.) +.IP \[bu] +The process is executing a set-user-ID (set-group-ID) program +that is owned by a user (group) other than the real user (group) +ID of the process, +or the process is executing a program that has file capabilities (see +.BR capabilities (7)). +(However, see the description of the +.BR prctl (2) +.B PR_SET_DUMPABLE +operation, and the description of the +.I /proc/sys/fs/suid_dumpable +.\" FIXME . Perhaps relocate discussion of /proc/sys/fs/suid_dumpable +.\" and PR_SET_DUMPABLE to this page? +file in +.BR proc (5).) +.IP \[bu] +.I /proc/sys/kernel/core_pattern +is empty and +.I /proc/sys/kernel/core_uses_pid +contains the value 0. +(These files are described below.) +Note that if +.I /proc/sys/kernel/core_pattern +is empty and +.I /proc/sys/kernel/core_uses_pid +contains the value 1, +core dump files will have names of the form +.IR .pid , +and such files are hidden unless one uses the +.BR ls (1) +.I \-a +option. +.IP \[bu] +(Since Linux 3.7) +.\" commit 046d662f481830e652ac34cd112249adde16452a +The kernel was configured without the +.B CONFIG_COREDUMP +option. +.PP +In addition, +a core dump may exclude part of the address space of the process if the +.BR madvise (2) +.B MADV_DONTDUMP +flag was employed. +.PP +On systems that employ +.BR systemd (1) +as the +.I init +framework, core dumps may instead be placed in a location determined by +.BR systemd (1). +See below for further details. +.\" +.SS Naming of core dump files +By default, a core dump file is named +.IR core , +but the +.I /proc/sys/kernel/core_pattern +file (since Linux 2.6 and 2.4.21) +can be set to define a template that is used to name core dump files. +The template can contain % specifiers which are substituted +by the following values when a core file is created: +.PP +.RS 4 +.PD 0 +.TP 4 +%% +A single % character. +.TP +%c +Core file size soft resource limit of crashing process (since Linux 2.6.24). +.TP +%d +.\" Added in git commit 12a2b4b2241e318b4f6df31228e4272d2c2968a1 +Dump mode\[em]same as value returned by +.BR prctl (2) +.B PR_GET_DUMPABLE +(since Linux 3.7). +.TP +%e +The process or thread's +.I comm +value, which typically is the same as the executable filename +(without path prefix, and truncated to a maximum of 15 characters), +but may have been modified to be something different; +see the discussion of +.IR /proc/ pid /comm +and +.IR /proc/ pid /task/ tid /comm +in +.BR proc (5). +.TP +%E +Pathname of executable, +with slashes (\[aq]/\[aq]) replaced by exclamation marks (\[aq]!\[aq]) +(since Linux 3.0). +.TP +%g +Numeric real GID of dumped process. +.TP +%h +Hostname (same as \fInodename\fP returned by \fBuname\fP(2)). +.TP +%i +TID of thread that triggered core dump, +as seen in the PID namespace in which the thread resides +.\" commit b03023ecbdb76c1dec86b41ed80b123c22783220 +(since Linux 3.18). +.TP +%I +TID of thread that triggered core dump, as seen in the initial PID namespace +.\" commit b03023ecbdb76c1dec86b41ed80b123c22783220 +(since Linux 3.18). +.TP +%p +PID of dumped process, +as seen in the PID namespace in which the process resides. +.TP +%P +.\" Added in git commit 65aafb1e7484b7434a0c1d4c593191ebe5776a2f +PID of dumped process, as seen in the initial PID namespace +(since Linux 3.12). +.TP +%s +Number of signal causing dump. +.TP +%t +Time of dump, expressed as seconds since the +Epoch, 1970-01-01 00:00:00 +0000 (UTC). +.TP +%u +Numeric real UID of dumped process. +.PD +.RE +.PP +A single % at the end of the template is dropped from the +core filename, as is the combination of a % followed by any +character other than those listed above. +All other characters in the template become a literal +part of the core filename. +The template may include \[aq]/\[aq] characters, which are interpreted +as delimiters for directory names. +The maximum size of the resulting core filename is 128 bytes (64 bytes +before Linux 2.6.19). +The default value in this file is "core". +For backward compatibility, if +.I /proc/sys/kernel/core_pattern +does not include +.I %p +and +.I /proc/sys/kernel/core_uses_pid +(see below) +is nonzero, then .PID will be appended to the core filename. +.PP +Paths are interpreted according to the settings that are active for the +crashing process. +That means the crashing process's mount namespace (see +.BR mount_namespaces (7)), +its current working directory (found via +.BR getcwd (2)), +and its root directory (see +.BR chroot (2)). +.PP +Since Linux 2.4, Linux has also provided +a more primitive method of controlling +the name of the core dump file. +If the +.I /proc/sys/kernel/core_uses_pid +file contains the value 0, then a core dump file is simply named +.IR core . +If this file contains a nonzero value, then the core dump file includes +the process ID in a name of the form +.IR core.PID . +.PP +Since Linux 3.6, +.\" 9520628e8ceb69fa9a4aee6b57f22675d9e1b709 +if +.I /proc/sys/fs/suid_dumpable +is set to 2 ("suidsafe"), the pattern must be either an absolute pathname +(starting with a leading \[aq]/\[aq] character) or a pipe, as defined below. +.SS Piping core dumps to a program +Since Linux 2.6.19, Linux supports an alternate syntax for the +.I /proc/sys/kernel/core_pattern +file. +If the first character of this file is a pipe symbol (\fB|\fP), +then the remainder of the line is interpreted as the command-line for +a user-space program (or script) that is to be executed. +.PP +Since Linux 5.3.0, +.\" commit 315c69261dd3fa12dbc830d4fa00d1fad98d3b03 +the pipe template is split on spaces into an argument list +.I before +the template parameters are expanded. +In earlier kernels, the template parameters are expanded first and +the resulting string is split on spaces into an argument list. +This means that in earlier kernels executable names added by the +.I %e +and +.I %E +template parameters could get split into multiple arguments. +So the core dump handler needs to put the executable names as the last +argument and ensure it joins all parts of the executable name using spaces. +Executable names with multiple spaces in them are not correctly represented +in earlier kernels, +meaning that the core dump handler needs to use mechanisms to find +the executable name. +.PP +Instead of being written to a file, the core dump is given as +standard input to the program. +Note the following points: +.IP \[bu] 3 +The program must be specified using an absolute pathname (or a +pathname relative to the root directory, \fI/\fP), +and must immediately follow the '|' character. +.IP \[bu] +The command-line arguments can include any of +the % specifiers listed above. +For example, to pass the PID of the process that is being dumped, specify +.I %p +in an argument. +.IP \[bu] +The process created to run the program runs as user and group +.IR root . +.IP \[bu] +Running as +.I root +does not confer any exceptional security bypasses. +Namely, LSMs (e.g., SELinux) are still active and may prevent the handler +from accessing details about the crashed process via +.IR /proc/ pid. +.IP \[bu] +The program pathname is interpreted with respect to the initial mount namespace +as it is always executed there. +It is not affected by the settings +(e.g., root directory, mount namespace, current working directory) +of the crashing process. +.IP \[bu] +The process runs in the initial namespaces +(PID, mount, user, and so on) +and not in the namespaces of the crashing process. +One can utilize specifiers such as +.I %P +to find the right +.IR /proc/ pid +directory and probe/enter the crashing process's namespaces if needed. +.IP \[bu] +The process starts with its current working directory +as the root directory. +If desired, it is possible change to the working directory of +the dumping process by employing the value provided by the +.I %P +specifier to change to the location of the dumping process via +.IR /proc/ pid /cwd . +.IP \[bu] +Command-line arguments can be supplied to the +program (since Linux 2.6.24), +delimited by white space (up to a total line length of 128 bytes). +.IP \[bu] +The +.B RLIMIT_CORE +limit is not enforced for core dumps that are piped to a program +via this mechanism. +.\" +.SS /proc/sys/kernel/core_pipe_limit +When collecting core dumps via a pipe to a user-space program, +it can be useful for the collecting program to gather data about +the crashing process from that process's +.IR /proc/ pid +directory. +In order to do this safely, +the kernel must wait for the program collecting the core dump to exit, +so as not to remove the crashing process's +.IR /proc/ pid +files prematurely. +This in turn creates the +possibility that a misbehaving collecting program can block +the reaping of a crashed process by simply never exiting. +.PP +Since Linux 2.6.32, +.\" commit a293980c2e261bd5b0d2a77340dd04f684caff58 +the +.I /proc/sys/kernel/core_pipe_limit +can be used to defend against this possibility. +The value in this file defines how many concurrent crashing +processes may be piped to user-space programs in parallel. +If this value is exceeded, then those crashing processes above this value +are noted in the kernel log and their core dumps are skipped. +.PP +A value of 0 in this file is special. +It indicates that unlimited processes may be captured in parallel, +but that no waiting will take place (i.e., the collecting +program is not guaranteed access to +.IR /proc/<crashing\-PID> ). +The default value for this file is 0. +.\" +.SS Controlling which mappings are written to the core dump +Since Linux 2.6.23, the Linux-specific +.IR /proc/ pid /coredump_filter +file can be used to control which memory segments are written to the +core dump file in the event that a core dump is performed for the +process with the corresponding process ID. +.PP +The value in the file is a bit mask of memory mapping types (see +.BR mmap (2)). +If a bit is set in the mask, then memory mappings of the +corresponding type are dumped; otherwise they are not dumped. +The bits in this file have the following meanings: +.PP +.PD 0 +.RS 4 +.TP +bit 0 +Dump anonymous private mappings. +.TP +bit 1 +Dump anonymous shared mappings. +.TP +bit 2 +Dump file-backed private mappings. +.TP +bit 3 +Dump file-backed shared mappings. +.\" file-backed shared mappings of course also update the underlying +.\" mapped file. +.TP +bit 4 (since Linux 2.6.24) +Dump ELF headers. +.TP +bit 5 (since Linux 2.6.28) +Dump private huge pages. +.TP +bit 6 (since Linux 2.6.28) +Dump shared huge pages. +.TP +bit 7 (since Linux 4.4) +.\" commit ab27a8d04b32b6ee8c30c14c4afd1058e8addc82 +Dump private DAX pages. +.TP +bit 8 (since Linux 4.4) +.\" commit ab27a8d04b32b6ee8c30c14c4afd1058e8addc82 +Dump shared DAX pages. +.RE +.PD +.PP +By default, the following bits are set: 0, 1, 4 (if the +.B CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS +kernel configuration option is enabled), and 5. +This default can be modified at boot time using the +.I coredump_filter +boot option. +.PP +The value of this file is displayed in hexadecimal. +(The default value is thus displayed as 33.) +.PP +Memory-mapped I/O pages such as frame buffer are never dumped, and +virtual DSO +.RB ( vdso (7)) +pages are always dumped, regardless of the +.I coredump_filter +value. +.PP +A child process created via +.BR fork (2) +inherits its parent's +.I coredump_filter +value; +the +.I coredump_filter +value is preserved across an +.BR execve (2). +.PP +It can be useful to set +.I coredump_filter +in the parent shell before running a program, for example: +.PP +.in +4n +.EX +.RB "$" " echo 0x7 > /proc/self/coredump_filter" +.RB "$" " ./some_program" +.EE +.in +.PP +This file is provided only if the kernel was built with the +.B CONFIG_ELF_CORE +configuration option. +.\" +.SS Core dumps and systemd +On systems using the +.BR systemd (1) +.I init +framework, core dumps may be placed in a location determined by +.BR systemd (1). +To do this, +.BR systemd (1) +employs the +.I core_pattern +feature that allows piping core dumps to a program. +One can verify this by checking whether core dumps are being piped to the +.BR systemd\-coredump (8) +program: +.PP +.in +4n +.EX +$ \fBcat /proc/sys/kernel/core_pattern\fP +|/usr/lib/systemd/systemd\-coredump %P %u %g %s %t %c %e +.EE +.in +.PP +In this case, core dumps will be placed in the location configured for +.BR systemd\-coredump (8), +typically as +.BR lz4 (1) +compressed files in the directory +.IR /var/lib/systemd/coredump/ . +One can list the core dumps that have been recorded by +.BR systemd\-coredump (8) +using +.BR coredumpctl (1): +.PP +.EX +$ \fBcoredumpctl list | tail \-5\fP +Wed 2017\-10\-11 22:25:30 CEST 2748 1000 1000 3 present /usr/bin/sleep +Thu 2017\-10\-12 06:29:10 CEST 2716 1000 1000 3 present /usr/bin/sleep +Thu 2017\-10\-12 06:30:50 CEST 2767 1000 1000 3 present /usr/bin/sleep +Thu 2017\-10\-12 06:37:40 CEST 2918 1000 1000 3 present /usr/bin/cat +Thu 2017\-10\-12 08:13:07 CEST 2955 1000 1000 3 present /usr/bin/cat +.EE +.PP +The information shown for each core dump includes the date and time +of the dump, the PID, UID, and GID of the dumping process, +the signal number that caused the core dump, +and the pathname of the executable that was being run by the dumped process. +Various options to +.BR coredumpctl (1) +allow a specified coredump file to be pulled from the +.BR systemd (1) +location into a specified file. +For example, to extract the core dump for PID 2955 shown above to a file named +.I core +in the current directory, one could use: +.PP +.in +4n +.EX +$ \fBcoredumpctl dump 2955 \-o core\fP +.EE +.in +.PP +For more extensive details, see the +.BR coredumpctl (1) +manual page. +.PP +To (persistently) disable the +.BR systemd (1) +mechanism that archives core dumps, restoring to something more like +traditional Linux behavior, one can set an override for the +.BR systemd (1) +mechanism, using something like: +.PP +.in +4n +.EX +# \fBecho "kernel.core_pattern=core.%p" > \e\fP +\fB /etc/sysctl.d/50\-coredump.conf\fP +# \fB/lib/systemd/systemd\-sysctl\fP +.EE +.in +.PP +It is also possible to temporarily (i.e., until the next reboot) change the +.I core_pattern +setting using a command such as the following +(which causes the names of core dump files to include the executable name +as well as the number of the signal which triggered the core dump): +.PP +.in +4n +.EX +# \fBsysctl \-w kernel.core_pattern="%e\-%s.core"\fP +.EE +.in +.\" +.SH NOTES +The +.BR gdb (1) +.I gcore +command can be used to obtain a core dump of a running process. +.PP +In Linux versions up to and including 2.6.27, +.\" Changed with commit 6409324b385f3f63a03645b4422e3be67348d922 +if a multithreaded process (or, more precisely, a process that +shares its memory with another process by being created with the +.B CLONE_VM +flag of +.BR clone (2)) +dumps core, then the process ID is always appended to the core filename, +unless the process ID was already included elsewhere in the +filename via a +.I %p +specification in +.IR /proc/sys/kernel/core_pattern . +(This is primarily useful when employing the obsolete +LinuxThreads implementation, +where each thread of a process has a different PID.) +.\" Always including the PID in the name of the core file made +.\" sense for LinuxThreads, where each thread had a unique PID, +.\" but doesn't seem to serve any purpose with NPTL, where all the +.\" threads in a process share the same PID (as POSIX.1 requires). +.\" Probably the behavior is maintained so that applications using +.\" LinuxThreads continue appending the PID (the kernel has no easy +.\" way of telling which threading implementation the user-space +.\" application is using). -- mtk, April 2006 +.SH EXAMPLES +The program below can be used to demonstrate the use of the +pipe syntax in the +.I /proc/sys/kernel/core_pattern +file. +The following shell session demonstrates the use of this program +(compiled to create an executable named +.IR core_pattern_pipe_test ): +.PP +.in +4n +.EX +.RB "$" " cc \-o core_pattern_pipe_test core_pattern_pipe_test.c" +.RB "$" " su" +Password: +.RB "#" " echo \[dq]|$PWD/core_pattern_pipe_test %p \ +UID=%u GID=%g sig=%s\[dq] > \e" +.B " /proc/sys/kernel/core_pattern" +.RB "#" " exit" +.RB "$" " sleep 100" +.BR "\[ha]\e" " # type control\-backslash" +Quit (core dumped) +.RB "$" " cat core.info" +argc=5 +argc[0]=</home/mtk/core_pattern_pipe_test> +argc[1]=<20575> +argc[2]=<UID=1000> +argc[3]=<GID=100> +argc[4]=<sig=3> +Total bytes in core dump: 282624 +.EE +.in +.SS Program source +\& +.EX +/* core_pattern_pipe_test.c */ +\& +#define _GNU_SOURCE +#include <sys/stat.h> +#include <fcntl.h> +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +\& +#define BUF_SIZE 1024 +\& +int +main(int argc, char *argv[]) +{ + ssize_t nread, tot; + char buf[BUF_SIZE]; + FILE *fp; + char cwd[PATH_MAX]; +\& + /* Change our current working directory to that of the + crashing process. */ +\& + snprintf(cwd, PATH_MAX, "/proc/%s/cwd", argv[1]); + chdir(cwd); +\& + /* Write output to file "core.info" in that directory. */ +\& + fp = fopen("core.info", "w+"); + if (fp == NULL) + exit(EXIT_FAILURE); +\& + /* Display command\-line arguments given to core_pattern + pipe program. */ +\& + fprintf(fp, "argc=%d\en", argc); + for (size_t j = 0; j < argc; j++) + fprintf(fp, "argc[%zu]=<%s>\en", j, argv[j]); +\& + /* Count bytes in standard input (the core dump). */ +\& + tot = 0; + while ((nread = read(STDIN_FILENO, buf, BUF_SIZE)) > 0) + tot += nread; + fprintf(fp, "Total bytes in core dump: %zd\en", tot); +\& + fclose(fp); + exit(EXIT_SUCCESS); +} +.EE +.SH SEE ALSO +.BR bash (1), +.BR coredumpctl (1), +.BR gdb (1), +.BR getrlimit (2), +.BR mmap (2), +.BR prctl (2), +.BR sigaction (2), +.BR elf (5), +.BR proc (5), +.BR pthreads (7), +.BR signal (7), +.BR systemd\-coredump (8) diff --git a/man5/dir_colors.5 b/man5/dir_colors.5 new file mode 100644 index 0000000..ccee252 --- /dev/null +++ b/man5/dir_colors.5 @@ -0,0 +1,406 @@ +'\" t +.\" Copyright (c) 2001 Martin Schulze <joey@infodrom.org> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.TH dir_colors 5 2023-07-15 "Linux man-pages 6.05.01" +.SH NAME +dir_colors \- configuration file for dircolors(1) +.SH DESCRIPTION +The program +.BR ls (1) +uses the environment variable +.B LS_COLORS +to determine the colors in which the filenames are to be displayed. +This environment variable is usually set by a command like +.PP +.RS +eval \`dircolors some_path/dir_colors\` +.RE +.PP +found in a system default shell initialization file, like +.I /etc/profile +or +.IR /etc/csh.cshrc . +(See also +.BR dircolors (1).) +Usually, the file used here is +.I /etc/DIR_COLORS +and can be overridden by a +.I .dir_colors +file in one's home directory. +.PP +This configuration file consists of several statements, one per line. +Anything right of a hash mark (#) is treated as a comment, if the +hash mark is at the beginning of a line or is preceded by at least one +whitespace. +Blank lines are ignored. +.PP +The +.I global +section of the file consists of any statement before the first +.B TERM +statement. +Any statement in the global section of the file is +considered valid for all terminal types. +Following the global section +is one or more +.I terminal-specific +sections, preceded by one or more +.B TERM +statements which specify the terminal types (as given by the +.B TERM +environment variable) the following declarations apply to. +It is always possible to override a global declaration by a subsequent +terminal-specific one. +.PP +The following statements are recognized; case is insignificant: +.TP +.B TERM \fIterminal-type\fR +Starts a terminal-specific section and specifies which terminal it +applies to. +Multiple +.B TERM +statements can be used to create a section which applies for several +terminal types. +.TP +.B COLOR yes|all|no|none|tty +(Slackware only; ignored by GNU +.BR dircolors (1).) +Specifies that colorization should always be enabled (\fIyes\fR or +\fIall\fR), never enabled (\fIno\fR or \fInone\fR), or enabled only if +the output is a terminal (\fItty\fR). +The default is \fIno\fR. +.TP +.B EIGHTBIT yes|no +(Slackware only; ignored by GNU +.BR dircolors (1).) +Specifies that eight-bit ISO 8859 characters should be enabled by +default. +For compatibility reasons, this can also be specified as 1 for +\fIyes\fR or 0 for \fIno\fR. +The default is \fIno\fR. +.TP +.B OPTIONS \fIoptions\fR +(Slackware only; ignored by GNU +.BR dircolors (1).) +Adds command-line options to the default +.B ls +command line. +The options can be any valid +.B ls +command-line options, and should include the leading minus sign. +Note that +.B dircolors +does not verify the validity of these options. +.TP +.B NORMAL \fIcolor-sequence\fR +Specifies the color used for normal (nonfilename) text. +.IP +Synonym: +.BR NORM . +.TP +.B FILE \fIcolor-sequence\fR +Specifies the color used for a regular file. +.TP +.B DIR \fIcolor-sequence\fR +Specifies the color used for directories. +.TP +.B LINK \fIcolor-sequence\fR +Specifies the color used for a symbolic link. +.IP +Synonyms: +.BR LNK , +.BR SYMLINK . +.TP +.B ORPHAN \fIcolor-sequence\fR +Specifies the color used for an orphaned symbolic link (one which +points to a nonexistent file). +If this is unspecified, +.B ls +will use the +.B LINK +color instead. +.TP +.B MISSING \fIcolor-sequence\fR +Specifies the color used for a missing file (a nonexistent file which +nevertheless has a symbolic link pointing to it). +If this is unspecified, +.B ls +will use the +.B FILE +color instead. +.TP +.B FIFO \fIcolor-sequence\fR +Specifies the color used for a FIFO (named pipe). +.IP +Synonym: +.BR PIPE . +.TP +.B SOCK \fIcolor-sequence\fR +Specifies the color used for a socket. +.TP +.B DOOR \fIcolor-sequence\fR +(Supported since fileutils 4.1) +Specifies the color used for a door (Solaris 2.5 and later). +.TP +.B BLK \fIcolor-sequence\fR +Specifies the color used for a block device special file. +.IP +Synonym: +.BR BLOCK . +.TP +.B CHR \fIcolor-sequence\fR +Specifies the color used for a character device special file. +.IP +Synonym: +.BR CHAR . +.TP +.B EXEC \fIcolor-sequence\fR +Specifies the color used for a file with the executable attribute set. +.TP +.B SUID \fIcolor-sequence\fR +Specifies the color used for a file with the set-user-ID attribute set. +.IP +Synonym: +.BR SETUID . +.TP +.B SGID \fIcolor-sequence\fR +Specifies the color used for a file with the set-group-ID attribute set. +.IP +Synonym: +.BR SETGID . +.TP +.B STICKY \fIcolor-sequence\fR +Specifies the color used for a directory with the sticky attribute set. +.TP +.B STICKY_OTHER_WRITABLE \fIcolor-sequence\fR +Specifies the color used for +an other-writable directory with the executable attribute set. +.IP +Synonym: +.BR OWT . +.TP +.B OTHER_WRITABLE \fIcolor-sequence\fR +Specifies the color used for +an other-writable directory without the executable attribute set. +.IP +Synonym: +.BR OWR . +.TP +.B LEFTCODE \fIcolor-sequence\fR +Specifies the +.I "left code" +for non-ISO\ 6429 terminals (see below). +.IP +Synonym: +.BR LEFT . +.TP +.B RIGHTCODE \fIcolor-sequence\fR +Specifies the +.I "right code" +for non-ISO\ 6429 terminals (see below). +.IP +Synonym: +.BR RIGHT . +.TP +.B ENDCODE \fIcolor-sequence\fR +Specifies the +.I "end code" +for non-ISO\ 6429 terminals (see below). +.IP +Synonym: +.BR END . +.TP +.BI * "extension color-sequence" +Specifies the color used for any file that ends in \fIextension\fR. +.TP +.BI . "extension color-sequence" +Same as \fB*\fR.\fIextension\fR. +Specifies the color used for any file that +ends in .\fIextension\fR. +Note that the period is included in the +extension, which makes it impossible to specify an extension not +starting with a period, such as +.B \[ti] +for +.B emacs +backup files. +This form should be considered obsolete. +.SS ISO 6429 (ANSI) color sequences +Most color-capable ASCII terminals today use ISO 6429 (ANSI) color sequences, +and many common terminals without color capability, including +.B xterm +and the widely used and cloned DEC VT100, will recognize ISO 6429 color +codes and harmlessly eliminate them from the output or emulate them. +.B ls +uses ISO 6429 codes by default, assuming colorization is enabled. +.PP +ISO 6429 color sequences are composed of sequences of numbers +separated by semicolons. +The most common codes are: +.RS +.TS +l l. + 0 to restore default color + 1 for brighter colors + 4 for underlined text + 5 for flashing text +30 for black foreground +31 for red foreground +32 for green foreground +33 for yellow (or brown) foreground +34 for blue foreground +35 for purple foreground +36 for cyan foreground +37 for white (or gray) foreground +40 for black background +41 for red background +42 for green background +43 for yellow (or brown) background +44 for blue background +45 for purple background +46 for cyan background +47 for white (or gray) background +.TE +.RE +.PP +Not all commands will work on all systems or display devices. +.PP +.B ls +uses the following defaults: +.TS +lb l l. +NORMAL 0 Normal (nonfilename) text +FILE 0 Regular file +DIR 32 Directory +LINK 36 Symbolic link +ORPHAN undefined Orphaned symbolic link +MISSING undefined Missing file +FIFO 31 Named pipe (FIFO) +SOCK 33 Socket +BLK 44;37 Block device +CHR 44;37 Character device +EXEC 35 Executable file +.TE +.PP +A few terminal programs do not recognize the default +properly. +If all text gets colorized after you do a directory +listing, change the +.B NORMAL +and +.B FILE +codes to the numerical codes for your normal foreground and background +colors. +.SS Other terminal types (advanced configuration) +If you have a color-capable (or otherwise highlighting) terminal (or +printer!) which uses a different set of codes, you can still generate +a suitable setup. +To do so, you will have to use the +.BR LEFTCODE , +.BR RIGHTCODE , +and +.B ENDCODE +definitions. +.PP +When writing out a filename, +.B ls +generates the following output sequence: +.B LEFTCODE +.I typecode +.B RIGHTCODE +.I filename +.BR ENDCODE , +where the +.I typecode +is the color sequence that depends on the type or name of file. +If the +.B ENDCODE +is undefined, the sequence +.B "LEFTCODE NORMAL RIGHTCODE" +will be used instead. +The purpose of the left- and rightcodes is +merely to reduce the amount of typing necessary (and to hide ugly +escape codes away from the user). +If they are not appropriate for +your terminal, you can eliminate them by specifying the respective +keyword on a line by itself. +.PP +.B NOTE: +If the +.B ENDCODE +is defined in the global section of the setup file, it +.I cannot +be undefined in a terminal-specific section of the file. +This means any +.B NORMAL +definition will have no effect. +A different +.B ENDCODE +can, however, be specified, which would have the same effect. +.SS Escape sequences +To specify control- or blank characters in the color sequences or +filename extensions, either C-style \e-escaped notation or +.BR stty \-style +\[ha]-notation can be used. +The C-style notation +includes the following characters: +.RS +.TS +lb l. +\ea Bell (ASCII 7) +\eb Backspace (ASCII 8) +\ee Escape (ASCII 27) +\ef Form feed (ASCII 12) +\en Newline (ASCII 10) +\er Carriage Return (ASCII 13) +\et Tab (ASCII 9) +\ev Vertical Tab (ASCII 11) +\e? Delete (ASCII 127) +\e\fInnn Any character (octal notation) +\ex\fInnn Any character (hexadecimal notation) +\e_ Space +\e\e Backslash (\e) +\e\[ha] Caret (\[ha]) +\e# Hash mark (#) +.TE +.RE +.PP +Note that escapes are necessary to enter a space, backslash, +caret, or any control character anywhere in the string, as well as a +hash mark as the first character. +.SH FILES +.TP +.I /etc/DIR_COLORS +System-wide configuration file. +.TP +.I \[ti]/.dir_colors +Per-user configuration file. +.PP +This page describes the +.B dir_colors +file format as used in the fileutils-4.1 package; +other versions may differ slightly. +.SH NOTES +The default +.B LEFTCODE +and +.B RIGHTCODE +definitions, which are used by ISO 6429 terminals are: +.RS +.TS +lb l. +LEFTCODE \ee[ +RIGHTCODE m +.TE +.RE +.PP +The default +.B ENDCODE +is undefined. +.SH SEE ALSO +.BR dircolors (1), +.BR ls (1), +.BR stty (1), +.BR xterm (1) diff --git a/man5/elf.5 b/man5/elf.5 new file mode 100644 index 0000000..6fa4ddf --- /dev/null +++ b/man5/elf.5 @@ -0,0 +1,2196 @@ +.\" $OpenBSD: elf.5,v 1.12 2003/10/27 20:23:58 jmc Exp $ +.\"Copyright (c) 1999 Jeroen Ruigrok van der Werven +.\"All rights reserved. +.\" +.\" %%%LICENSE_START(PERMISSIVE_MISC) +.\"Redistribution and use in source and binary forms, with or without +.\"modification, are permitted provided that the following conditions +.\"are met: +.\"1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\"2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\"THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\"ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\"IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\"ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\"FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\"DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\"OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\"HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\"LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\"OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\"SUCH DAMAGE. +.\" %%%LICENSE_END +.\" +.\" $FreeBSD: src/share/man/man5/elf.5,v 1.21 2001/10/01 16:09:23 ru Exp $ +.\" +.\" Slightly adapted - aeb, 2004-01-01 +.\" 2005-07-15, Mike Frysinger <vapier@gentoo.org>, various fixes +.\" 2007-10-11, Mike Frysinger <vapier@gentoo.org>, various fixes +.\" 2007-12-08, mtk, Converted from mdoc to man macros +.\" +.TH ELF 5 2023-05-03 "Linux man-pages 6.05.01" +.SH NAME +elf \- format of Executable and Linking Format (ELF) files +.SH SYNOPSIS +.nf +.\" .B #include <elf_abi.h> +.B #include <elf.h> +.fi +.SH DESCRIPTION +The header file +.I <elf.h> +defines the format of ELF executable binary files. +Amongst these files are +normal executable files, relocatable object files, core files, and shared +objects. +.PP +An executable file using the ELF file format consists of an ELF header, +followed by a program header table or a section header table, or both. +The ELF header is always at offset zero of the file. +The program header +table and the section header table's offset in the file are defined in the +ELF header. +The two tables describe the rest of the particularities of +the file. +.PP +.\" Applications which wish to process ELF binary files for their native +.\" architecture only should include +.\" .I <elf_abi.h> +.\" in their source code. +.\" These applications should need to refer to +.\" all the types and structures by their generic names +.\" "Elf_xxx" +.\" and to the macros by +.\" ELF_xxx". +.\" Applications written this way can be compiled on any architecture, +.\" regardless of whether the host is 32-bit or 64-bit. +.\" .PP +.\" Should an application need to process ELF files of an unknown +.\" architecture, then the application needs to explicitly use either +.\" "Elf32_xxx" +.\" or +.\" "Elf64_xxx" +.\" type and structure names. +.\" Likewise, the macros need to be identified by +.\" "ELF32_xxx" +.\" or +.\" "ELF64_xxx". +.\" .PP +This header file describes the above mentioned headers as C structures +and also includes structures for dynamic sections, relocation sections and +symbol tables. +.\" +.SS Basic types +The following types are used for N-bit architectures (N=32,64, +.I ElfN +stands for +.I Elf32 +or +.IR Elf64 , +.I uintN_t +stands for +.I uint32_t +or +.IR uint64_t ): +.PP +.in +4n +.EX +ElfN_Addr Unsigned program address, uintN_t +ElfN_Off Unsigned file offset, uintN_t +ElfN_Section Unsigned section index, uint16_t +ElfN_Versym Unsigned version symbol information, uint16_t +Elf_Byte unsigned char +ElfN_Half uint16_t +ElfN_Sword int32_t +ElfN_Word uint32_t +ElfN_Sxword int64_t +ElfN_Xword uint64_t +.\" Elf32_Size Unsigned object size +.EE +.in +.PP +(Note: the *BSD terminology is a bit different. +There, +.I Elf64_Half +is +twice as large as +.IR Elf32_Half , +and +.I Elf64Quarter +is used for +.IR uint16_t . +In order to avoid confusion these types are replaced by explicit ones +in the below.) +.PP +All data structures that the file format defines follow the +"natural" +size and alignment guidelines for the relevant class. +If necessary, +data structures contain explicit padding to ensure 4-byte alignment +for 4-byte objects, to force structure sizes to a multiple of 4, and so on. +.\" +.SS ELF header (Ehdr) +The ELF header is described by the type +.I Elf32_Ehdr +or +.IR Elf64_Ehdr : +.PP +.in +4n +.EX +#define EI_NIDENT 16 +\& +typedef struct { + unsigned char e_ident[EI_NIDENT]; + uint16_t e_type; + uint16_t e_machine; + uint32_t e_version; + ElfN_Addr e_entry; + ElfN_Off e_phoff; + ElfN_Off e_shoff; + uint32_t e_flags; + uint16_t e_ehsize; + uint16_t e_phentsize; + uint16_t e_phnum; + uint16_t e_shentsize; + uint16_t e_shnum; + uint16_t e_shstrndx; +} ElfN_Ehdr; +.EE +.in +.PP +The fields have the following meanings: +.\" +.\" +.TP +.I e_ident +This array of bytes specifies how to interpret the file, +independent of the processor or the file's remaining contents. +Within this array everything is named by macros, which start with +the prefix +.B EI_ +and may contain values which start with the prefix +.BR ELF . +The following macros are defined: +.RS +.TP +.B EI_MAG0 +The first byte of the magic number. +It must be filled with +.BR ELFMAG0 . +(0: 0x7f) +.TP +.B EI_MAG1 +The second byte of the magic number. +It must be filled with +.BR ELFMAG1 . +(1: \[aq]E\[aq]) +.TP +.B EI_MAG2 +The third byte of the magic number. +It must be filled with +.BR ELFMAG2 . +(2: \[aq]L\[aq]) +.TP +.B EI_MAG3 +The fourth byte of the magic number. +It must be filled with +.BR ELFMAG3 . +(3: \[aq]F\[aq]) +.TP +.B EI_CLASS +The fifth byte identifies the architecture for this binary: +.RS +.TP 14 +.PD 0 +.B ELFCLASSNONE +This class is invalid. +.TP +.B ELFCLASS32 +This defines the 32-bit architecture. +It supports machines with files +and virtual address spaces up to 4 Gigabytes. +.TP +.B ELFCLASS64 +This defines the 64-bit architecture. +.PD +.RE +.TP +.B EI_DATA +The sixth byte specifies the data encoding of the processor-specific +data in the file. +Currently, these encodings are supported: +.RS 9 +.TP 14 +.PD 0 +.B ELFDATANONE +Unknown data format. +.TP +.B ELFDATA2LSB +Two's complement, little-endian. +.TP +.B ELFDATA2MSB +Two's complement, big-endian. +.PD +.RE +.TP +.B EI_VERSION +The seventh byte is the version number of the ELF specification: +.IP +.PD 0 +.RS +.TP 14 +.B EV_NONE +Invalid version. +.TP +.B EV_CURRENT +Current version. +.PD +.RE +.\".El +.TP +.B EI_OSABI +The eighth byte identifies the operating system +and ABI to which the object is targeted. +Some fields in other ELF structures have flags +and values that have platform-specific meanings; +the interpretation of those fields is determined by the value of this byte. +For example: +.RS +.TP 21 +.PD 0 +.B ELFOSABI_NONE +Same as ELFOSABI_SYSV +.\" 0 +.TP +.B ELFOSABI_SYSV +UNIX System V ABI +.\" 0 +.\" synonym: ELFOSABI_NONE +.TP +.B ELFOSABI_HPUX +HP-UX ABI +.\" 1 +.TP +.B ELFOSABI_NETBSD +NetBSD ABI +.\" 2 +.TP +.B ELFOSABI_LINUX +Linux ABI +.\" 3 +.\" .TP +.\" .BR ELFOSABI_HURD +.\" Hurd ABI +.\" 4 +.\" .TP +.\" .BR ELFOSABI_86OPEN +.\" 86Open Common IA32 ABI +.\" 5 +.TP +.B ELFOSABI_SOLARIS +Solaris ABI +.\" 6 +.\" .TP +.\" .BR ELFOSABI_MONTEREY +.\" Monterey project ABI +.\" Now replaced by +.\" ELFOSABI_AIX +.\" 7 +.TP +.B ELFOSABI_IRIX +IRIX ABI +.\" 8 +.TP +.B ELFOSABI_FREEBSD +FreeBSD ABI +.\" 9 +.TP +.B ELFOSABI_TRU64 +TRU64 UNIX ABI +.\" 10 +.\" ELFOSABI_MODESTO +.\" 11 +.\" ELFOSABI_OPENBSD +.\" 12 +.TP +.B ELFOSABI_ARM +ARM architecture ABI +.\" 97 +.TP +.B ELFOSABI_STANDALONE +Stand-alone (embedded) ABI +.\" 255 +.PD +.RE +.TP +.B EI_ABIVERSION +The ninth byte identifies the version of the ABI +to which the object is targeted. +This field is used to distinguish among incompatible versions of an ABI. +The interpretation of this version number +is dependent on the ABI identified by the +.B EI_OSABI +field. +Applications conforming to this specification use the value 0. +.TP +.B EI_PAD +Start of padding. +These bytes are reserved and set to zero. +Programs +which read them should ignore them. +The value for +.B EI_PAD +will change in +the future if currently unused bytes are given meanings. +.\" As reported by Yuri Kozlov and confirmed by Mike Frysinger, EI_BRAND is +.\" not in GABI (http://www.sco.com/developers/gabi/latest/ch4.eheader.html) +.\" It looks to be a BSDism +.\" .TP +.\" .BR EI_BRAND +.\" Start of architecture identification. +.TP +.B EI_NIDENT +The size of the +.I e_ident +array. +.RE +.TP +.I e_type +This member of the structure identifies the object file type: +.RS +.TP 16 +.PD 0 +.B ET_NONE +An unknown type. +.TP +.B ET_REL +A relocatable file. +.TP +.B ET_EXEC +An executable file. +.TP +.B ET_DYN +A shared object. +.TP +.B ET_CORE +A core file. +.PD +.RE +.TP +.I e_machine +This member specifies the required architecture for an individual file. +For example: +.RS +.TP 16 +.PD 0 +.B EM_NONE +An unknown machine +.\" 0 +.TP +.B EM_M32 +AT&T WE 32100 +.\" 1 +.TP +.B EM_SPARC +Sun Microsystems SPARC +.\" 2 +.TP +.B EM_386 +Intel 80386 +.\" 3 +.TP +.B EM_68K +Motorola 68000 +.\" 4 +.TP +.B EM_88K +Motorola 88000 +.\" 5 +.\" .TP +.\" .BR EM_486 +.\" Intel 80486 +.\" 6 +.TP +.B EM_860 +Intel 80860 +.\" 7 +.TP +.B EM_MIPS +MIPS RS3000 (big-endian only) +.\" 8 +.\" EM_S370 +.\" 9 +.\" .TP +.\" .BR EM_MIPS_RS4_BE +.\" MIPS RS4000 (big-endian only). Deprecated +.\" 10 +.\" EM_MIPS_RS3_LE (MIPS R3000 little-endian) +.\" 10 +.TP +.B EM_PARISC +HP/PA +.\" 15 +.TP +.B EM_SPARC32PLUS +SPARC with enhanced instruction set +.\" 18 +.TP +.B EM_PPC +PowerPC +.\" 20 +.TP +.B EM_PPC64 +PowerPC 64-bit +.\" 21 +.TP +.B EM_S390 +IBM S/390 +.\" 22 +.TP +.B EM_ARM +Advanced RISC Machines +.\" 40 +.TP +.B EM_SH +Renesas SuperH +.\" 42 +.TP +.B EM_SPARCV9 +SPARC v9 64-bit +.\" 43 +.TP +.B EM_IA_64 +Intel Itanium +.\" 50 +.TP +.B EM_X86_64 +AMD x86-64 +.\" 62 +.TP +.B EM_VAX +DEC Vax +.\" 75 +.\" EM_CRIS +.\" 76 +.\" .TP +.\" .BR EM_ALPHA +.\" Compaq [DEC] Alpha +.\" .TP +.\" .BR EM_ALPHA_EXP +.\" Compaq [DEC] Alpha with enhanced instruction set +.PD +.RE +.TP +.I e_version +This member identifies the file version: +.RS +.TP 16 +.PD 0 +.B EV_NONE +Invalid version +.TP +.B EV_CURRENT +Current version +.PD +.RE +.TP +.I e_entry +This member gives the virtual address to which the system first transfers +control, thus starting the process. +If the file has no associated entry +point, this member holds zero. +.TP +.I e_phoff +This member holds the program header table's file offset in bytes. +If +the file has no program header table, this member holds zero. +.TP +.I e_shoff +This member holds the section header table's file offset in bytes. +If the +file has no section header table, this member holds zero. +.TP +.I e_flags +This member holds processor-specific flags associated with the file. +Flag names take the form EF_`machine_flag'. +Currently, no flags have been defined. +.TP +.I e_ehsize +This member holds the ELF header's size in bytes. +.TP +.I e_phentsize +This member holds the size in bytes of one entry in the file's +program header table; all entries are the same size. +.TP +.I e_phnum +This member holds the number of entries in the program header +table. +Thus the product of +.I e_phentsize +and +.I e_phnum +gives the table's size +in bytes. +If a file has no program header, +.I e_phnum +holds the value zero. +.IP +If the number of entries in the program header table is +larger than or equal to +.\" This is a Linux extension, added in Linux 2.6.34. +.B PN_XNUM +(0xffff), this member holds +.B PN_XNUM +(0xffff) and the real number of entries in the program header table is held +in the +.I sh_info +member of the initial entry in section header table. +Otherwise, the +.I sh_info +member of the initial entry contains the value zero. +.RS +.TP +.B PN_XNUM +This is defined as 0xffff, the largest number +.I e_phnum +can have, specifying where the actual number of program headers is assigned. +.PD +.RE +.TP +.I e_shentsize +This member holds a sections header's size in bytes. +A section header is one +entry in the section header table; all entries are the same size. +.TP +.I e_shnum +This member holds the number of entries in the section header table. +Thus +the product of +.I e_shentsize +and +.I e_shnum +gives the section header table's size in bytes. +If a file has no section +header table, +.I e_shnum +holds the value of zero. +.IP +If the number of entries in the section header table is +larger than or equal to +.B SHN_LORESERVE +(0xff00), +.I e_shnum +holds the value zero and the real number of entries in the section header +table is held in the +.I sh_size +member of the initial entry in section header table. +Otherwise, the +.I sh_size +member of the initial entry in the section header table holds +the value zero. +.TP +.I e_shstrndx +This member holds the section header table index of the entry associated +with the section name string table. +If the file has no section name string +table, this member holds the value +.BR SHN_UNDEF . +.IP +If the index of section name string table section is +larger than or equal to +.B SHN_LORESERVE +(0xff00), this member holds +.B SHN_XINDEX +(0xffff) and the real index of the section name string table section +is held in the +.I sh_link +member of the initial entry in section header table. +Otherwise, the +.I sh_link +member of the initial entry in section header table contains the value zero. +.\" +.SS Program header (Phdr) +An executable or shared object file's program header table is an array of +structures, each describing a segment or other information the system needs +to prepare the program for execution. +An object file +.I segment +contains one or more +.IR sections . +Program headers are meaningful only for executable and shared object files. +A file specifies its own program header size with the ELF header's +.I e_phentsize +and +.I e_phnum +members. +The ELF program header is described by the type +.I Elf32_Phdr +or +.I Elf64_Phdr +depending on the architecture: +.PP +.in +4n +.EX +typedef struct { + uint32_t p_type; + Elf32_Off p_offset; + Elf32_Addr p_vaddr; + Elf32_Addr p_paddr; + uint32_t p_filesz; + uint32_t p_memsz; + uint32_t p_flags; + uint32_t p_align; +} Elf32_Phdr; +.EE +.in +.PP +.in +4n +.EX +typedef struct { + uint32_t p_type; + uint32_t p_flags; + Elf64_Off p_offset; + Elf64_Addr p_vaddr; + Elf64_Addr p_paddr; + uint64_t p_filesz; + uint64_t p_memsz; + uint64_t p_align; +} Elf64_Phdr; +.EE +.in +.PP +The main difference between the 32-bit and the 64-bit program header lies +in the location of the +.I p_flags +member in the total struct. +.TP +.I p_type +This member of the structure indicates what kind of segment this array +element describes or how to interpret the array element's information. +.RS 10 +.TP +.B PT_NULL +The array element is unused and the other members' values are undefined. +This lets the program header have ignored entries. +.TP +.B PT_LOAD +The array element specifies a loadable segment, described by +.I p_filesz +and +.IR p_memsz . +The bytes from the file are mapped to the beginning of the memory +segment. +If the segment's memory size +.I p_memsz +is larger than the file size +.IR p_filesz , +the +"extra" +bytes are defined to hold the value 0 and to follow the segment's +initialized area. +The file size may not be larger than the memory size. +Loadable segment entries in the program header table appear in ascending +order, sorted on the +.I p_vaddr +member. +.TP +.B PT_DYNAMIC +The array element specifies dynamic linking information. +.TP +.B PT_INTERP +The array element specifies the location and size of a null-terminated +pathname to invoke as an interpreter. +This segment type is meaningful +only for executable files (though it may occur for shared objects). +However it may not occur more than once in a file. +If it is present, it must precede any loadable segment entry. +.TP +.B PT_NOTE +The array element specifies the location of notes (ElfN_Nhdr). +.TP +.B PT_SHLIB +This segment type is reserved but has unspecified semantics. +Programs that +contain an array element of this type do not conform to the ABI. +.TP +.B PT_PHDR +The array element, if present, +specifies the location and size of the program header table itself, +both in the file and in the memory image of the program. +This segment type may not occur more than once in a file. +Moreover, it may +occur only if the program header table is part of the memory image of the +program. +If it is present, it must precede any loadable segment entry. +.TP +.BR PT_LOPROC ", " PT_HIPROC +Values in the inclusive range +.RB [ PT_LOPROC , +.BR PT_HIPROC ] +are reserved for processor-specific semantics. +.TP +.B PT_GNU_STACK +GNU extension which is used by the Linux kernel to control the state of the +stack via the flags set in the +.I p_flags +member. +.RE +.TP +.I p_offset +This member holds the offset from the beginning of the file at which +the first byte of the segment resides. +.TP +.I p_vaddr +This member holds the virtual address at which the first byte of the +segment resides in memory. +.TP +.I p_paddr +On systems for which physical addressing is relevant, this member is +reserved for the segment's physical address. +Under +BSD +this member is +not used and must be zero. +.TP +.I p_filesz +This member holds the number of bytes in the file image of the segment. +It may be zero. +.TP +.I p_memsz +This member holds the number of bytes in the memory image of the segment. +It may be zero. +.TP +.I p_flags +This member holds a bit mask of flags relevant to the segment: +.RS +.TP +.PD 0 +.B PF_X +An executable segment. +.TP +.B PF_W +A writable segment. +.TP +.B PF_R +A readable segment. +.PD +.RE +.IP +A text segment commonly has the flags +.B PF_X +and +.B PF_R . +A data segment commonly has +.B PF_W +and +.BR PF_R . +.TP +.I p_align +This member holds the value to which the segments are aligned in memory +and in the file. +Loadable process segments must have congruent values for +.I p_vaddr +and +.IR p_offset , +modulo the page size. +Values of zero and one mean no alignment is required. +Otherwise, +.I p_align +should be a positive, integral power of two, and +.I p_vaddr +should equal +.IR p_offset , +modulo +.IR p_align . +.\" +.SS Section header (Shdr) +A file's section header table lets one locate all the file's sections. +The +section header table is an array of +.I Elf32_Shdr +or +.I Elf64_Shdr +structures. +The +ELF header's +.I e_shoff +member gives the byte offset from the beginning of the file to the section +header table. +.I e_shnum +holds the number of entries the section header table contains. +.I e_shentsize +holds the size in bytes of each entry. +.PP +A section header table index is a subscript into this array. +Some section +header table indices are reserved: +the initial entry and the indices between +.B SHN_LORESERVE +and +.BR SHN_HIRESERVE . +The initial entry is used in ELF extensions for +.IR e_phnum , +.IR e_shnum , +and +.IR e_shstrndx ; +in other cases, each field in the initial entry is set to zero. +An object file does not have sections for +these special indices: +.TP +.B SHN_UNDEF +This value marks an undefined, missing, irrelevant, +or otherwise meaningless section reference. +.TP +.B SHN_LORESERVE +This value specifies the lower bound of the range of reserved indices. +.TP +.BR SHN_LOPROC ", " SHN_HIPROC +Values greater in the inclusive range +.RB [ SHN_LOPROC , +.BR SHN_HIPROC ] +are reserved for processor-specific semantics. +.TP +.B SHN_ABS +This value specifies the absolute value for the corresponding reference. +For +example, a symbol defined relative to section number +.B SHN_ABS +has an absolute value and is not affected by relocation. +.TP +.B SHN_COMMON +Symbols defined relative to this section are common symbols, +such as FORTRAN COMMON or unallocated C external variables. +.TP +.B SHN_HIRESERVE +This value specifies the upper bound of the range of reserved indices. +The +system reserves indices between +.B SHN_LORESERVE +and +.BR SHN_HIRESERVE , +inclusive. +The section header table does not contain entries for the +reserved indices. +.PP +The section header has the following structure: +.PP +.in +4n +.EX +typedef struct { + uint32_t sh_name; + uint32_t sh_type; + uint32_t sh_flags; + Elf32_Addr sh_addr; + Elf32_Off sh_offset; + uint32_t sh_size; + uint32_t sh_link; + uint32_t sh_info; + uint32_t sh_addralign; + uint32_t sh_entsize; +} Elf32_Shdr; +.EE +.in +.PP +.in +4n +.EX +typedef struct { + uint32_t sh_name; + uint32_t sh_type; + uint64_t sh_flags; + Elf64_Addr sh_addr; + Elf64_Off sh_offset; + uint64_t sh_size; + uint32_t sh_link; + uint32_t sh_info; + uint64_t sh_addralign; + uint64_t sh_entsize; +} Elf64_Shdr; +.EE +.in +.PP +No real differences exist between the 32-bit and 64-bit section headers. +.TP +.I sh_name +This member specifies the name of the section. +Its value is an index +into the section header string table section, giving the location of +a null-terminated string. +.TP +.I sh_type +This member categorizes the section's contents and semantics. +.RS +.TP +.B SHT_NULL +This value marks the section header as inactive. +It does not +have an associated section. +Other members of the section header +have undefined values. +.TP +.B SHT_PROGBITS +This section holds information defined by the program, whose +format and meaning are determined solely by the program. +.TP +.B SHT_SYMTAB +This section holds a symbol table. +Typically, +.B SHT_SYMTAB +provides symbols for link editing, though it may also be used +for dynamic linking. +As a complete symbol table, it may contain +many symbols unnecessary for dynamic linking. +An object file can +also contain a +.B SHT_DYNSYM +section. +.TP +.B SHT_STRTAB +This section holds a string table. +An object file may have multiple +string table sections. +.TP +.B SHT_RELA +This section holds relocation entries with explicit addends, such +as type +.I Elf32_Rela +for the 32-bit class of object files. +An object may have multiple +relocation sections. +.TP +.B SHT_HASH +This section holds a symbol hash table. +An object participating in +dynamic linking must contain a symbol hash table. +An object file may +have only one hash table. +.TP +.B SHT_DYNAMIC +This section holds information for dynamic linking. +An object file may +have only one dynamic section. +.TP +.B SHT_NOTE +This section holds notes (ElfN_Nhdr). +.TP +.B SHT_NOBITS +A section of this type occupies no space in the file but otherwise +resembles +.BR SHT_PROGBITS . +Although this section contains no bytes, the +.I sh_offset +member contains the conceptual file offset. +.TP +.B SHT_REL +This section holds relocation offsets without explicit addends, such +as type +.I Elf32_Rel +for the 32-bit class of object files. +An object file may have multiple +relocation sections. +.TP +.B SHT_SHLIB +This section is reserved but has unspecified semantics. +.TP +.B SHT_DYNSYM +This section holds a minimal set of dynamic linking symbols. +An +object file can also contain a +.B SHT_SYMTAB +section. +.TP +.BR SHT_LOPROC ", " SHT_HIPROC +Values in the inclusive range +.RB [ SHT_LOPROC , +.BR SHT_HIPROC ] +are reserved for processor-specific semantics. +.TP +.B SHT_LOUSER +This value specifies the lower bound of the range of indices reserved for +application programs. +.TP +.B SHT_HIUSER +This value specifies the upper bound of the range of indices reserved for +application programs. +Section types between +.B SHT_LOUSER +and +.B SHT_HIUSER +may be used by the application, without conflicting with current or future +system-defined section types. +.RE +.TP +.I sh_flags +Sections support one-bit flags that describe miscellaneous attributes. +If a flag bit is set in +.IR sh_flags , +the attribute is +"on" +for the section. +Otherwise, the attribute is +"off" +or does not apply. +Undefined attributes are set to zero. +.RS +.TP +.B SHF_WRITE +This section contains data that should be writable during process +execution. +.TP +.B SHF_ALLOC +This section occupies memory during process execution. +Some control +sections do not reside in the memory image of an object file. +This +attribute is off for those sections. +.TP +.B SHF_EXECINSTR +This section contains executable machine instructions. +.TP +.B SHF_MASKPROC +All bits included in this mask are reserved for processor-specific +semantics. +.RE +.TP +.I sh_addr +If this section appears in the memory image of a process, this member +holds the address at which the section's first byte should reside. +Otherwise, the member contains zero. +.TP +.I sh_offset +This member's value holds the byte offset from the beginning of the file +to the first byte in the section. +One section type, +.BR SHT_NOBITS , +occupies no space in the file, and its +.I sh_offset +member locates the conceptual placement in the file. +.TP +.I sh_size +This member holds the section's size in bytes. +Unless the section type +is +.BR SHT_NOBITS , +the section occupies +.I sh_size +bytes in the file. +A section of type +.B SHT_NOBITS +may have a nonzero size, but it occupies no space in the file. +.TP +.I sh_link +This member holds a section header table index link, whose interpretation +depends on the section type. +.TP +.I sh_info +This member holds extra information, whose interpretation depends on the +section type. +.TP +.I sh_addralign +Some sections have address alignment constraints. +If a section holds a +doubleword, the system must ensure doubleword alignment for the entire +section. +That is, the value of +.I sh_addr +must be congruent to zero, modulo the value of +.IR sh_addralign . +Only zero and positive integral powers of two are allowed. +The value 0 or 1 means that the section has no alignment constraints. +.TP +.I sh_entsize +Some sections hold a table of fixed-sized entries, such as a symbol table. +For such a section, this member gives the size in bytes for each entry. +This member contains zero if the section does not hold a table of +fixed-size entries. +.PP +Various sections hold program and control information: +.TP +.I .bss +This section holds uninitialized data that contributes to the program's +memory image. +By definition, the system initializes the data with zeros +when the program begins to run. +This section is of type +.BR SHT_NOBITS . +The attribute types are +.B SHF_ALLOC +and +.BR SHF_WRITE . +.TP +.I .comment +This section holds version control information. +This section is of type +.BR SHT_PROGBITS . +No attribute types are used. +.TP +.I .ctors +This section holds initialized pointers to the C++ constructor functions. +This section is of type +.BR SHT_PROGBITS . +The attribute types are +.B SHF_ALLOC +and +.BR SHF_WRITE . +.TP +.I .data +This section holds initialized data that contribute to the program's +memory image. +This section is of type +.BR SHT_PROGBITS . +The attribute types are +.B SHF_ALLOC +and +.BR SHF_WRITE . +.TP +.I .data1 +This section holds initialized data that contribute to the program's +memory image. +This section is of type +.BR SHT_PROGBITS . +The attribute types are +.B SHF_ALLOC +and +.BR SHF_WRITE . +.TP +.I .debug +This section holds information for symbolic debugging. +The contents +are unspecified. +This section is of type +.BR SHT_PROGBITS . +No attribute types are used. +.TP +.I .dtors +This section holds initialized pointers to the C++ destructor functions. +This section is of type +.BR SHT_PROGBITS . +The attribute types are +.B SHF_ALLOC +and +.BR SHF_WRITE . +.TP +.I .dynamic +This section holds dynamic linking information. +The section's attributes +will include the +.B SHF_ALLOC +bit. +Whether the +.B SHF_WRITE +bit is set is processor-specific. +This section is of type +.BR SHT_DYNAMIC . +See the attributes above. +.TP +.I .dynstr +This section holds strings needed for dynamic linking, most commonly +the strings that represent the names associated with symbol table entries. +This section is of type +.BR SHT_STRTAB . +The attribute type used is +.BR SHF_ALLOC . +.TP +.I .dynsym +This section holds the dynamic linking symbol table. +This section is of type +.BR SHT_DYNSYM . +The attribute used is +.BR SHF_ALLOC . +.TP +.I .fini +This section holds executable instructions that contribute to the process +termination code. +When a program exits normally the system arranges to +execute the code in this section. +This section is of type +.BR SHT_PROGBITS . +The attributes used are +.B SHF_ALLOC +and +.BR SHF_EXECINSTR . +.TP +.I .gnu.version +This section holds the version symbol table, an array of +.I ElfN_Half +elements. +This section is of type +.BR SHT_GNU_versym . +The attribute type used is +.BR SHF_ALLOC . +.TP +.I .gnu.version_d +This section holds the version symbol definitions, a table of +.I ElfN_Verdef +structures. +This section is of type +.BR SHT_GNU_verdef . +The attribute type used is +.BR SHF_ALLOC . +.TP +.I .gnu.version_r +This section holds the version symbol needed elements, a table of +.I ElfN_Verneed +structures. +This section is of +type +.BR SHT_GNU_versym . +The attribute type used is +.BR SHF_ALLOC . +.TP +.I .got +This section holds the global offset table. +This section is of type +.BR SHT_PROGBITS . +The attributes are processor-specific. +.TP +.I .hash +This section holds a symbol hash table. +This section is of type +.BR SHT_HASH . +The attribute used is +.BR SHF_ALLOC . +.TP +.I .init +This section holds executable instructions that contribute to the process +initialization code. +When a program starts to run the system arranges to execute +the code in this section before calling the main program entry point. +This section is of type +.BR SHT_PROGBITS . +The attributes used are +.B SHF_ALLOC +and +.BR SHF_EXECINSTR . +.TP +.I .interp +This section holds the pathname of a program interpreter. +If the file has +a loadable segment that includes the section, the section's attributes will +include the +.B SHF_ALLOC +bit. +Otherwise, that bit will be off. +This section is of type +.BR SHT_PROGBITS . +.TP +.I .line +This section holds line number information for symbolic debugging, +which describes the correspondence between the program source and +the machine code. +The contents are unspecified. +This section is of type +.BR SHT_PROGBITS . +No attribute types are used. +.TP +.I .note +This section holds various notes. +This section is of type +.BR SHT_NOTE . +No attribute types are used. +.TP +.I .note.ABI\-tag +This section is used to declare the expected run-time ABI of the ELF image. +It may include the operating system name and its run-time versions. +This section is of type +.BR SHT_NOTE . +The only attribute used is +.BR SHF_ALLOC . +.TP +.I .note.gnu.build\-id +This section is used to hold an ID that uniquely identifies +the contents of the ELF image. +Different files with the same build ID should contain the same executable +content. +See the +.B \-\-build\-id +option to the GNU linker (\fBld\fR (1)) for more details. +This section is of type +.BR SHT_NOTE . +The only attribute used is +.BR SHF_ALLOC . +.TP +.I .note.GNU\-stack +This section is used in Linux object files for declaring stack attributes. +This section is of type +.BR SHT_PROGBITS . +The only attribute used is +.BR SHF_EXECINSTR . +This indicates to the GNU linker that the object file requires an +executable stack. +.TP +.I .note.openbsd.ident +OpenBSD native executables usually contain this section +to identify themselves so the kernel can bypass any compatibility +ELF binary emulation tests when loading the file. +.TP +.I .plt +This section holds the procedure linkage table. +This section is of type +.BR SHT_PROGBITS . +The attributes are processor-specific. +.TP +.I .relNAME +This section holds relocation information as described below. +If the file +has a loadable segment that includes relocation, the section's attributes +will include the +.B SHF_ALLOC +bit. +Otherwise, the bit will be off. +By convention, +"NAME" +is supplied by the section to which the relocations apply. +Thus a relocation +section for +.B .text +normally would have the name +.BR .rel.text . +This section is of type +.BR SHT_REL . +.TP +.I .relaNAME +This section holds relocation information as described below. +If the file +has a loadable segment that includes relocation, the section's attributes +will include the +.B SHF_ALLOC +bit. +Otherwise, the bit will be off. +By convention, +"NAME" +is supplied by the section to which the relocations apply. +Thus a relocation +section for +.B .text +normally would have the name +.BR .rela.text . +This section is of type +.BR SHT_RELA . +.TP +.I .rodata +This section holds read-only data that typically contributes to a +nonwritable segment in the process image. +This section is of type +.BR SHT_PROGBITS . +The attribute used is +.BR SHF_ALLOC . +.TP +.I .rodata1 +This section holds read-only data that typically contributes to a +nonwritable segment in the process image. +This section is of type +.BR SHT_PROGBITS . +The attribute used is +.BR SHF_ALLOC . +.TP +.I .shstrtab +This section holds section names. +This section is of type +.BR SHT_STRTAB . +No attribute types are used. +.TP +.I .strtab +This section holds strings, most commonly the strings that represent the +names associated with symbol table entries. +If the file has a loadable +segment that includes the symbol string table, the section's attributes +will include the +.B SHF_ALLOC +bit. +Otherwise, the bit will be off. +This section is of type +.BR SHT_STRTAB . +.TP +.I .symtab +This section holds a symbol table. +If the file has a loadable segment +that includes the symbol table, the section's attributes will include +the +.B SHF_ALLOC +bit. +Otherwise, the bit will be off. +This section is of type +.BR SHT_SYMTAB . +.TP +.I .text +This section holds the +"text", +or executable instructions, of a program. +This section is of type +.BR SHT_PROGBITS . +The attributes used are +.B SHF_ALLOC +and +.BR SHF_EXECINSTR . +.\" +.SS String and symbol tables +String table sections hold null-terminated character sequences, commonly +called strings. +The object file uses these strings to represent symbol +and section names. +One references a string as an index into the string +table section. +The first byte, which is index zero, is defined to hold +a null byte (\[aq]\e0\[aq]). +Similarly, a string table's last byte is defined to +hold a null byte, ensuring null termination for all strings. +.PP +An object file's symbol table holds information needed to locate and +relocate a program's symbolic definitions and references. +A symbol table +index is a subscript into this array. +.PP +.in +4n +.EX +typedef struct { + uint32_t st_name; + Elf32_Addr st_value; + uint32_t st_size; + unsigned char st_info; + unsigned char st_other; + uint16_t st_shndx; +} Elf32_Sym; +.EE +.in +.PP +.in +4n +.EX +typedef struct { + uint32_t st_name; + unsigned char st_info; + unsigned char st_other; + uint16_t st_shndx; + Elf64_Addr st_value; + uint64_t st_size; +} Elf64_Sym; +.EE +.in +.PP +The 32-bit and 64-bit versions have the same members, just in a different +order. +.TP +.I st_name +This member holds an index into the object file's symbol string table, +which holds character representations of the symbol names. +If the value +is nonzero, it represents a string table index that gives the symbol +name. +Otherwise, the symbol has no name. +.TP +.I st_value +This member gives the value of the associated symbol. +.TP +.I st_size +Many symbols have associated sizes. +This member holds zero if the symbol +has no size or an unknown size. +.TP +.I st_info +This member specifies the symbol's type and binding attributes: +.RS +.TP +.B STT_NOTYPE +The symbol's type is not defined. +.TP +.B STT_OBJECT +The symbol is associated with a data object. +.TP +.B STT_FUNC +The symbol is associated with a function or other executable code. +.TP +.B STT_SECTION +The symbol is associated with a section. +Symbol table entries of +this type exist primarily for relocation and normally have +.B STB_LOCAL +bindings. +.TP +.B STT_FILE +By convention, the symbol's name gives the name of the source file +associated with the object file. +A file symbol has +.B STB_LOCAL +bindings, its section index is +.BR SHN_ABS , +and it precedes the other +.B STB_LOCAL +symbols of the file, if it is present. +.TP +.BR STT_LOPROC ", " STT_HIPROC +Values in the inclusive range +.RB [ STT_LOPROC , +.BR STT_HIPROC ] +are reserved for processor-specific semantics. +.TP +.B STB_LOCAL +Local symbols are not visible outside the object file containing their +definition. +Local symbols of the same name may exist in multiple files +without interfering with each other. +.TP +.B STB_GLOBAL +Global symbols are visible to all object files being combined. +One file's +definition of a global symbol will satisfy another file's undefined +reference to the same symbol. +.TP +.B STB_WEAK +Weak symbols resemble global symbols, but their definitions have lower +precedence. +.TP +.BR STB_LOPROC ", " STB_HIPROC +Values in the inclusive range +.RB [ STB_LOPROC , +.BR STB_HIPROC ] +are reserved for processor-specific semantics. +.RE +.IP +There are macros for packing and unpacking the binding and type fields: +.RS +.TP +.BR ELF32_ST_BIND( \fIinfo\fP ) ", " ELF64_ST_BIND( \fIinfo\fP ) +Extract a binding from an +.I st_info +value. +.TP +.BR ELF32_ST_TYPE( \fIinfo ) ", " ELF64_ST_TYPE( \fIinfo\fP ) +Extract a type from an +.I st_info +value. +.TP +.BR ELF32_ST_INFO( \fIbind\fP ", " \fItype\fP ) ", " \ +ELF64_ST_INFO( \fIbind\fP ", " \fItype\fP ) +Convert a binding and a type into an +.I st_info +value. +.RE +.TP +.I st_other +This member defines the symbol visibility. +.RS +.TP +.PD 0 +.B STV_DEFAULT +Default symbol visibility rules. +Global and weak symbols are available to other modules; +references in the local module can be interposed +by definitions in other modules. +.TP +.B STV_INTERNAL +Processor-specific hidden class. +.TP +.B STV_HIDDEN +Symbol is unavailable to other modules; +references in the local module always resolve to the local symbol +(i.e., the symbol can't be interposed by definitions in other modules). +.TP +.B STV_PROTECTED +Symbol is available to other modules, +but references in the local module always resolve to the local symbol. +.PD +.PP +There are macros for extracting the visibility type: +.PP +.BR ELF32_ST_VISIBILITY (other) +or +.BR ELF64_ST_VISIBILITY (other) +.RE +.TP +.I st_shndx +Every symbol table entry is +"defined" +in relation to some section. +This member holds the relevant section +header table index. +.\" +.SS Relocation entries (Rel & Rela) +Relocation is the process of connecting symbolic references with +symbolic definitions. +Relocatable files must have information that +describes how to modify their section contents, thus allowing executable +and shared object files to hold the right information for a process's +program image. +Relocation entries are these data. +.PP +Relocation structures that do not need an addend: +.PP +.in +4n +.EX +typedef struct { + Elf32_Addr r_offset; + uint32_t r_info; +} Elf32_Rel; +.EE +.in +.PP +.in +4n +.EX +typedef struct { + Elf64_Addr r_offset; + uint64_t r_info; +} Elf64_Rel; +.EE +.in +.PP +Relocation structures that need an addend: +.PP +.in +4n +.EX +typedef struct { + Elf32_Addr r_offset; + uint32_t r_info; + int32_t r_addend; +} Elf32_Rela; +.EE +.in +.PP +.in +4n +.EX +typedef struct { + Elf64_Addr r_offset; + uint64_t r_info; + int64_t r_addend; +} Elf64_Rela; +.EE +.in +.TP +.I r_offset +This member gives the location at which to apply the relocation action. +For a relocatable file, the value is the byte offset from the beginning +of the section to the storage unit affected by the relocation. +For an +executable file or shared object, the value is the virtual address of +the storage unit affected by the relocation. +.TP +.I r_info +This member gives both the symbol table index with respect to which the +relocation must be made and the type of relocation to apply. +Relocation +types are processor-specific. +When the text refers to a relocation +entry's relocation type or symbol table index, it means the result of +applying +.B ELF[32|64]_R_TYPE +or +.BR ELF[32|64]_R_SYM , +respectively, to the entry's +.I r_info +member. +.TP +.I r_addend +This member specifies a constant addend used to compute the value to be +stored into the relocatable field. +.\" +.SS Dynamic tags (Dyn) +The +.I .dynamic +section contains a series of structures that hold relevant +dynamic linking information. +The +.I d_tag +member controls the interpretation +of +.IR d_un . +.PP +.in +4n +.EX +typedef struct { + Elf32_Sword d_tag; + union { + Elf32_Word d_val; + Elf32_Addr d_ptr; + } d_un; +} Elf32_Dyn; +extern Elf32_Dyn _DYNAMIC[]; +.EE +.in +.PP +.in +4n +.EX +typedef struct { + Elf64_Sxword d_tag; + union { + Elf64_Xword d_val; + Elf64_Addr d_ptr; + } d_un; +} Elf64_Dyn; +extern Elf64_Dyn _DYNAMIC[]; +.EE +.in +.TP +.I d_tag +This member may have any of the following values: +.RS +.TP 12 +.B DT_NULL +Marks end of dynamic section +.TP +.B DT_NEEDED +String table offset to name of a needed library +.TP +.B DT_PLTRELSZ +Size in bytes of PLT relocation entries +.TP +.B DT_PLTGOT +Address of PLT and/or GOT +.TP +.B DT_HASH +Address of symbol hash table +.TP +.B DT_STRTAB +Address of string table +.TP +.B DT_SYMTAB +Address of symbol table +.TP +.B DT_RELA +Address of Rela relocation table +.TP +.B DT_RELASZ +Size in bytes of the Rela relocation table +.TP +.B DT_RELAENT +Size in bytes of a Rela relocation table entry +.TP +.B DT_STRSZ +Size in bytes of string table +.TP +.B DT_SYMENT +Size in bytes of a symbol table entry +.TP +.B DT_INIT +Address of the initialization function +.TP +.B DT_FINI +Address of the termination function +.TP +.B DT_SONAME +String table offset to name of shared object +.TP +.B DT_RPATH +String table offset to library search path (deprecated) +.TP +.B DT_SYMBOLIC +Alert linker to search this shared object before the executable for symbols +.TP +.B DT_REL +Address of Rel relocation table +.TP +.B DT_RELSZ +Size in bytes of Rel relocation table +.TP +.B DT_RELENT +Size in bytes of a Rel table entry +.TP +.B DT_PLTREL +Type of relocation entry to which the PLT refers (Rela or Rel) +.TP +.B DT_DEBUG +Undefined use for debugging +.TP +.B DT_TEXTREL +Absence of this entry indicates that no relocation entries should +apply to a nonwritable segment +.TP +.B DT_JMPREL +Address of relocation entries associated solely with the PLT +.TP +.B DT_BIND_NOW +Instruct dynamic linker to process all relocations before +transferring control to the executable +.TP +.B DT_RUNPATH +String table offset to library search path +.TP +.BR DT_LOPROC ", " DT_HIPROC +Values in the inclusive range +.RB [ DT_LOPROC , +.BR DT_HIPROC ] +are reserved for processor-specific semantics +.RE +.TP +.I d_val +This member represents integer values with various interpretations. +.TP +.I d_ptr +This member represents program virtual addresses. +When interpreting +these addresses, the actual address should be computed based on the +original file value and memory base address. +Files do not contain +relocation entries to fixup these addresses. +.TP +.I _DYNAMIC +Array containing all the dynamic structures in the +.I .dynamic +section. +This is automatically populated by the linker. +.\" GABI ELF Reference for Note Sections: +.\" http://www.sco.com/developers/gabi/latest/ch5.pheader.html#note_section +.\" +.\" Note that it implies the sizes and alignments of notes depend on the ELF +.\" size (e.g. 32-bit ELFs have three 4-byte words and use 4-byte alignment +.\" while 64-bit ELFs use 8-byte words & alignment), but that is not the case +.\" in the real world. Notes always have three 4-byte words as can be seen +.\" in the source links below (remember that Elf64_Word is a 32-bit quantity). +.\" glibc: https://sourceware.org/git/?p=glibc.git;a=blob;f=elf/elf.h;h=9e59b3275917549af0cebe1f2de9ded3b7b10bf2#l1173 +.\" binutils: https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=binutils/readelf.c;h=274ddd17266aef6e4ad1f67af8a13a21500ff2af#l15943 +.\" Linux: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/elf.h?h=v4.8#n422 +.\" Solaris: https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-18048.html +.\" FreeBSD: https://svnweb.freebsd.org/base/head/sys/sys/elf_common.h?revision=303677&view=markup#l33 +.\" NetBSD: https://www.netbsd.org/docs/kernel/elf-notes.html +.\" OpenBSD: https://github.com/openbsd/src/blob/master/sys/sys/exec_elf.h#L533 +.\" +.SS Notes (Nhdr) +ELF notes allow for appending arbitrary information for the system to use. +They are largely used by core files +.RI ( e_type +of +.BR ET_CORE ), +but many projects define their own set of extensions. +For example, +the GNU tool chain uses ELF notes to pass information from +the linker to the C library. +.PP +Note sections contain a series of notes (see the +.I struct +definitions below). +Each note is followed by the name field (whose length is defined in +\fIn_namesz\fR) and then by the descriptor field (whose length is defined in +\fIn_descsz\fR) and whose starting address has a 4 byte alignment. +Neither field is defined in the note struct due to their arbitrary lengths. +.PP +An example for parsing out two consecutive notes should clarify their layout +in memory: +.PP +.in +4n +.EX +void *memory, *name, *desc; +Elf64_Nhdr *note, *next_note; +\& +/* The buffer is pointing to the start of the section/segment. */ +note = memory; +\& +/* If the name is defined, it follows the note. */ +name = note\->n_namesz == 0 ? NULL : memory + sizeof(*note); +\& +/* If the descriptor is defined, it follows the name + (with alignment). */ +\& +desc = note\->n_descsz == 0 ? NULL : + memory + sizeof(*note) + ALIGN_UP(note\->n_namesz, 4); +\& +/* The next note follows both (with alignment). */ +next_note = memory + sizeof(*note) + + ALIGN_UP(note\->n_namesz, 4) + + ALIGN_UP(note\->n_descsz, 4); +.EE +.in +.PP +Keep in mind that the interpretation of +.I n_type +depends on the namespace defined by the +.I n_namesz +field. +If the +.I n_namesz +field is not set (e.g., is 0), then there are two sets of notes: +one for core files and one for all other ELF types. +If the namespace is unknown, then tools will usually fallback to these sets +of notes as well. +.PP +.in +4n +.EX +typedef struct { + Elf32_Word n_namesz; + Elf32_Word n_descsz; + Elf32_Word n_type; +} Elf32_Nhdr; +.EE +.in +.PP +.in +4n +.EX +typedef struct { + Elf64_Word n_namesz; + Elf64_Word n_descsz; + Elf64_Word n_type; +} Elf64_Nhdr; +.EE +.in +.TP +.I n_namesz +The length of the name field in bytes. +The contents will immediately follow this note in memory. +The name is null terminated. +For example, if the name is "GNU", then +.I n_namesz +will be set to 4. +.TP +.I n_descsz +The length of the descriptor field in bytes. +The contents will immediately follow the name field in memory. +.TP +.I n_type +Depending on the value of the name field, this member may have any of the +following values: +.RS +.TP 5 +.B Core files (e_type = ET_CORE) +Notes used by all core files. +These are highly operating system or architecture specific and often require +close coordination with kernels, C libraries, and debuggers. +These are used when the namespace is the default (i.e., +.I n_namesz +will be set to 0), or a fallback when the namespace is unknown. +.RS +.TP 21 +.PD 0 +.B NT_PRSTATUS +prstatus struct +.TP +.B NT_FPREGSET +fpregset struct +.TP +.B NT_PRPSINFO +prpsinfo struct +.TP +.B NT_PRXREG +prxregset struct +.TP +.B NT_TASKSTRUCT +task structure +.TP +.B NT_PLATFORM +String from sysinfo(SI_PLATFORM) +.TP +.B NT_AUXV +auxv array +.TP +.B NT_GWINDOWS +gwindows struct +.TP +.B NT_ASRS +asrset struct +.TP +.B NT_PSTATUS +pstatus struct +.TP +.B NT_PSINFO +psinfo struct +.TP +.B NT_PRCRED +prcred struct +.TP +.B NT_UTSNAME +utsname struct +.TP +.B NT_LWPSTATUS +lwpstatus struct +.TP +.B NT_LWPSINFO +lwpinfo struct +.TP +.B NT_PRFPXREG +fprxregset struct +.TP +.B NT_SIGINFO +siginfo_t (size might increase over time) +.TP +.B NT_FILE +Contains information about mapped files +.TP +.B NT_PRXFPREG +user_fxsr_struct +.TP +.B NT_PPC_VMX +PowerPC Altivec/VMX registers +.TP +.B NT_PPC_SPE +PowerPC SPE/EVR registers +.TP +.B NT_PPC_VSX +PowerPC VSX registers +.TP +.B NT_386_TLS +i386 TLS slots (struct user_desc) +.TP +.B NT_386_IOPERM +x86 io permission bitmap (1=deny) +.TP +.B NT_X86_XSTATE +x86 extended state using xsave +.TP +.B NT_S390_HIGH_GPRS +s390 upper register halves +.TP +.B NT_S390_TIMER +s390 timer register +.TP +.B NT_S390_TODCMP +s390 time-of-day (TOD) clock comparator register +.TP +.B NT_S390_TODPREG +s390 time-of-day (TOD) programmable register +.TP +.B NT_S390_CTRS +s390 control registers +.TP +.B NT_S390_PREFIX +s390 prefix register +.TP +.B NT_S390_LAST_BREAK +s390 breaking event address +.TP +.B NT_S390_SYSTEM_CALL +s390 system call restart data +.TP +.B NT_S390_TDB +s390 transaction diagnostic block +.TP +.B NT_ARM_VFP +ARM VFP/NEON registers +.TP +.B NT_ARM_TLS +ARM TLS register +.TP +.B NT_ARM_HW_BREAK +ARM hardware breakpoint registers +.TP +.B NT_ARM_HW_WATCH +ARM hardware watchpoint registers +.TP +.B NT_ARM_SYSTEM_CALL +ARM system call number +.PD +.RE +.TP +.B n_name = GNU +Extensions used by the GNU tool chain. +.RS +.TP +.B NT_GNU_ABI_TAG +Operating system (OS) ABI information. +The desc field will be 4 words: +.IP +.PD 0 +.RS +.IP [0] 5 +OS descriptor +(\fBELF_NOTE_OS_LINUX\fR, \fBELF_NOTE_OS_GNU\fR, and so on)` +.IP [1] +major version of the ABI +.IP [2] +minor version of the ABI +.IP [3] +subminor version of the ABI +.RE +.PD +.TP +.B NT_GNU_HWCAP +Synthetic hwcap information. +The desc field begins with two words: +.IP +.PD 0 +.RS +.IP [0] 5 +number of entries +.IP [1] +bit mask of enabled entries +.RE +.PD +.IP +Then follow variable-length entries, one byte followed by a null-terminated +hwcap name string. +The byte gives the bit number to test if enabled, (1U << bit) & bit mask. +.TP +.B NT_GNU_BUILD_ID +Unique build ID as generated by the GNU +.BR ld (1) +.B \-\-build\-id +option. +The desc consists of any nonzero number of bytes. +.TP +.B NT_GNU_GOLD_VERSION +The desc contains the GNU Gold linker version used. +.RE +.TP +.B Default/unknown namespace (e_type != ET_CORE) +These are used when the namespace is the default (i.e., +.I n_namesz +will be set to 0), or a fallback when the namespace is unknown. +.RS +.TP 12 +.PD 0 +.B NT_VERSION +A version string of some sort. +.TP +.B NT_ARCH +Architecture information. +.PD +.RE +.RE +.SH NOTES +.\" OpenBSD +.\" ELF support first appeared in +.\" OpenBSD 1.2, +.\" although not all supported platforms use it as the native +.\" binary file format. +ELF first appeared in +System V. +The ELF format is an adopted standard. +.PP +The extensions for +.IR e_phnum , +.IR e_shnum , +and +.I e_shstrndx +respectively are +Linux extensions. +Sun, BSD, and AMD64 also support them; for further information, +look under SEE ALSO. +.\" .SH AUTHORS +.\" The original version of this manual page was written by +.\" .An Jeroen Ruigrok van der Werven +.\" .Aq asmodai@FreeBSD.org +.\" with inspiration from BSDi's +.\" .Bsx +.\" .Nm elf +.\" man page. +.SH SEE ALSO +.BR as (1), +.BR elfedit (1), +.BR gdb (1), +.BR ld (1), +.BR nm (1), +.BR objcopy (1), +.BR objdump (1), +.BR patchelf (1), +.BR readelf (1), +.BR size (1), +.BR strings (1), +.BR strip (1), +.BR execve (2), +.BR dl_iterate_phdr (3), +.BR core (5), +.BR ld.so (8) +.PP +Hewlett-Packard, +.IR "Elf-64 Object File Format" . +.PP +Santa Cruz Operation, +.IR "System V Application Binary Interface" . +.PP +UNIX System Laboratories, +"Object Files", +.IR "Executable and Linking Format (ELF)" . +.PP +Sun Microsystems, +.IR "Linker and Libraries Guide" . +.PP +AMD64 ABI Draft, +.IR "System V Application Binary Interface AMD64 Architecture Processor Supplement" . diff --git a/man5/erofs.5 b/man5/erofs.5 new file mode 100644 index 0000000..97edfdc --- /dev/null +++ b/man5/erofs.5 @@ -0,0 +1,97 @@ +.\" Copyright (c) 2016 by Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH erofs 5 2023-04-29 "Linux man-pages 6.05.01" +.SH NAME +erofs \- the Enhanced Read-Only File System +.SH DESCRIPTION +.B erofs +is a create-once read-only filesystem, +with support for compression and a multi-device backing store. +.PP +There are two inode formats: +.IP \[bu] 3 +32-byte compact with 16-bit UID/GID, +32-bit file size, +and no file times +.PD 0 +.IP \[bu] +64-byte extended with 32-bit UID/GID, +64-bit file size, +and a modification time +.RI ( st_mtim ). +.PD +.\" See fs/erofs/super.c:shmem_parse_options for options it supports. +.SS Mount options +.TP +.B user_xattr +.TQ +.B nouser_xattr +Controls whether +.I user +extended attributes are exposed. +Defaults to yes. +.TP +.B acl +.TQ +.B noacl +Controls whether POSIX +.BR acl (5)s +are exposed. +Defaults to yes. +.TP +.BR cache_strategy = disabled | readahead | readaround +Cache allocation for compressed files: +never, if reading from start of file, regardless of position. +Defaults to +.BR readaround . +.TP +.B dax +.TQ +.BR dax = always | never +Direct Access control. +If +.B always +and the source device supports DAX, uncompressed non-inlined files +will be read directly, without going through the page cache. +.B dax +is a synonym for +.BR always . +Defaults to unset, which is equivalent to +.BR never . +.TP +.BR device = \fIblobdev\fP +Add extra device holding some of the data. +Must be given as many times and in the same order as +.B \-\-blobdev +was to +.BR mkfs.erofs (1). +.\" Nominally there's a device_table feature and it somehow scans(?) for them, +.\" cf. super.c:erofs_scan_devices(), but I haven't gotten it to work +.TP +.BR domain_id = \fIdid\fP +.TQ +.BR fsid = \fIid\fP +Control CacheFiles on-demand read support. +To be documented. +.SH VERSIONS +.B erofs +images are versioned through the use of feature flags; +these are listed in the +.B \-E +section of +.BR mkfs.erofs (1), +.SH CONFIGURATION +Linux must be configured with the +.B CONFIG_EROFS_FS +option to mount EROFS filesystems. +There are sub-configuration items that restrict the availability +of some of the parameters above. +.SH SEE ALSO +.BR mkfs.erofs (1), +.BR fsck.erofs (1), +.BR dump.erofs (1) +.PP +.I Documentation/filesystems/erofs.txt +in the Linux source. diff --git a/man5/filesystems.5 b/man5/filesystems.5 new file mode 100644 index 0000000..cc76699 --- /dev/null +++ b/man5/filesystems.5 @@ -0,0 +1,227 @@ +.\" Copyright 1996 Daniel Quinlan (Daniel.Quinlan@linux.org) +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" 2007-12-14 mtk Added Reiserfs, XFS, JFS. +.\" +.TH filesystems 5 2023-04-10 "Linux man-pages 6.05.01" +.nh +.SH NAME +filesystems \- Linux filesystem types: ext, ext2, ext3, ext4, hpfs, iso9660, +JFS, minix, msdos, ncpfs nfs, ntfs, proc, Reiserfs, smb, sysv, umsdos, vfat, +XFS, xiafs +.SH DESCRIPTION +When, as is customary, the +.B proc +filesystem is mounted on +.IR /proc , +you can find in the file +.I /proc/filesystems +which filesystems your kernel currently supports; +see +.BR proc (5) +for more details. +There is also a legacy +.BR sysfs (2) +system call (whose availability is controlled by the +.\" commit: 6af9f7bf3c399e0ab1eee048e13572c6d4e15fe9 +.B CONFIG_SYSFS_SYSCALL +kernel build configuration option since Linux 3.15) +that enables enumeration of the currently available filesystem types +regardless of +.I /proc +availability and/or sanity. +.PP +If you need a currently unsupported filesystem, insert the corresponding +kernel module or recompile the kernel. +.PP +In order to use a filesystem, you have to +.I mount +it; see +.BR mount (2) +and +.BR mount (8). +.PP +The following list provides a +short description of the available or historically available +filesystems in the Linux kernel. +See the kernel documentation for a comprehensive +description of all options and limitations. +.TP +.B erofs +is the Enhanced Read-Only File System, stable since Linux 5.4. +.\" commit 47e4937a4a7ca4184fd282791dfee76c6799966a moves it out of staging +See +.BR erofs (5). +.TP +.B ext +is an elaborate extension of the +.B minix +filesystem. +It has been completely superseded by the second version +of the extended filesystem +.RB ( ext2 ) +and has been removed from the kernel (in Linux 2.1.21). +.TP +.B ext2 +is a disk filesystem that was used by Linux for fixed disks +as well as removable media. +The second extended filesystem was designed as an extension of the +extended filesystem +.RB ( ext ). +See +.BR ext2 (5). +.TP +.B ext3 +is a journaling version of the +.B ext2 +filesystem. +It is easy to +switch back and forth between +.B ext2 +and +.BR ext3 . +See +.BR ext3 (5). +.TP +.B ext4 +is a set of upgrades to +.B ext3 +including substantial performance and +reliability enhancements, +plus large increases in volume, file, and directory size limits. +See +.BR ext4 (5). +.TP +.B hpfs +is the High Performance Filesystem, used in OS/2. +This filesystem is +read-only under Linux due to the lack of available documentation. +.TP +.B iso9660 +is a CD-ROM filesystem type conforming to the ISO 9660 standard. +.RS +.TP +.B "High Sierra" +Linux supports High Sierra, the precursor to the ISO 9660 standard for +CD-ROM filesystems. +It is automatically recognized within the +.B iso9660 +filesystem support under Linux. +.TP +.B "Rock Ridge" +Linux also supports the System Use Sharing Protocol records specified +by the Rock Ridge Interchange Protocol. +They are used to further describe the files in the +.B iso9660 +filesystem to a UNIX host, and provide information such as long +filenames, UID/GID, POSIX permissions, and devices. +It is automatically recognized within the +.B iso9660 +filesystem support under Linux. +.RE +.TP +.B JFS +is a journaling filesystem, developed by IBM, +that was integrated into Linux 2.4.24. +.TP +.B minix +is the filesystem used in the Minix operating system, the first to run +under Linux. +It has a number of shortcomings, including a 64\ MB partition size +limit, short filenames, and a single timestamp. +It remains useful for floppies and RAM disks. +.TP +.B msdos +is the filesystem used by DOS, Windows, and some OS/2 computers. +.B msdos +filenames can be no longer than 8 characters, followed by an +optional period and 3 character extension. +.TP +.B ncpfs +is a network filesystem that supports the NCP protocol, +used by Novell NetWare. +It was removed from the kernel in Linux 4.17. +.IP +To use +.BR ncpfs , +you need special programs, which can be found at +.UR ftp://ftp.gwdg.de\:/pub\:/linux\:/misc\:/ncpfs +.UE . +.TP +.B nfs +is the network filesystem used to access disks located on remote computers. +.TP +.B ntfs +is the filesystem native to Microsoft Windows NT, +supporting features like ACLs, journaling, encryption, and so on. +.TP +.B proc +is a pseudo filesystem which is used as an interface to kernel data +structures rather than reading and interpreting +.IR /dev/kmem . +In particular, its files do not take disk space. +See +.BR proc (5). +.TP +.B Reiserfs +is a journaling filesystem, designed by Hans Reiser, +that was integrated into Linux 2.4.1. +.TP +.B smb +is a network filesystem that supports the SMB protocol, used by +Windows. +See +.UR https://www.samba.org\:/samba\:/smbfs/ +.UE . +.TP +.B sysv +is an implementation of the System V/Coherent filesystem for Linux. +It implements all of Xenix FS, System V/386 FS, and Coherent FS. +.TP +.B umsdos +is an extended DOS filesystem used by Linux. +It adds capability for +long filenames, UID/GID, POSIX permissions, and special files +(devices, named pipes, etc.) under the DOS filesystem, without +sacrificing compatibility with DOS. +.TP +.B tmpfs +is a filesystem whose contents reside in virtual memory. +Since the files on such filesystems typically reside in RAM, +file access is extremely fast. +See +.BR tmpfs (5). +.TP +.B vfat +is an extended FAT filesystem used by Microsoft Windows95 and Windows NT. +.B vfat +adds the capability to use long filenames under the MSDOS filesystem. +.TP +.B XFS +is a journaling filesystem, developed by SGI, +that was integrated into Linux 2.4.20. +.TP +.B xiafs +was designed and implemented to be a stable, safe filesystem by +extending the Minix filesystem code. +It provides the basic most +requested features without undue complexity. +The +.B xiafs +filesystem is no longer actively developed or maintained. +It was removed from the kernel in Linux 2.1.21. +.SH SEE ALSO +.BR fuse (4), +.BR btrfs (5), +.BR ext2 (5), +.BR ext3 (5), +.BR ext4 (5), +.BR nfs (5), +.BR proc (5), +.BR sysfs (5), +.BR tmpfs (5), +.BR xfs (5), +.BR fsck (8), +.BR mkfs (8), +.BR mount (8) diff --git a/man5/fs.5 b/man5/fs.5 new file mode 100644 index 0000000..3ec300c --- /dev/null +++ b/man5/fs.5 @@ -0,0 +1 @@ +.so man5/filesystems.5 diff --git a/man5/ftpusers.5 b/man5/ftpusers.5 new file mode 100644 index 0000000..9af5c52 --- /dev/null +++ b/man5/ftpusers.5 @@ -0,0 +1,42 @@ +.\" Copyright (c) 2000 Christoph J. Thompson <obituary@linuxbe.org> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.TH ftpusers 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +ftpusers \- list of users that may not log in via the FTP daemon +.SH DESCRIPTION +The text file +.B ftpusers +contains a list of users that may not log in using the +File Transfer Protocol (FTP) server daemon. +This file is used not merely for +system administration purposes but also for improving security within a TCP/IP +networked environment. +.PP +The +.B ftpusers +file will typically contain a list of the users that +either have no business using ftp or have too many privileges to be allowed +to log in through the FTP server daemon. +Such users usually include root, daemon, bin, uucp, and news. +.PP +If your FTP server daemon doesn't use +.BR ftpusers , +then it is suggested that you read its documentation to find out how to +block access for certain users. +Washington University FTP server Daemon +(wuftpd) and Professional FTP Daemon (proftpd) are known to make use of +.BR ftpusers . +.SS Format +The format of +.B ftpusers +is very simple. +There is one account name (or username) per line. +Lines starting with a # are ignored. +.SH FILES +.I /etc/ftpusers +.SH SEE ALSO +.BR passwd (5), +.BR proftpd (8), +.BR wuftpd (8) diff --git a/man5/gai.conf.5 b/man5/gai.conf.5 new file mode 100644 index 0000000..bba4480 --- /dev/null +++ b/man5/gai.conf.5 @@ -0,0 +1,89 @@ +.\" Copyright (C) 2006 Red Hat, Inc. All rights reserved. +.\" Author: Ulrich Drepper <drepper@redhat.com> +.\" +.\" SPDX-License-Identifier: GPL-2.0-only +.\" +.TH gai.conf 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +gai.conf \- getaddrinfo(3) configuration file +.SH DESCRIPTION +A call to +.BR getaddrinfo (3) +might return multiple answers. +According to RFC\ 3484 these answers must be sorted so that +the answer with the highest success rate is first in the list. +The RFC provides an algorithm for the sorting. +The static rules are not always adequate, though. +For this reason, +the RFC also requires that system administrators should have the possibility +to dynamically change the sorting. +For the glibc implementation, this can be achieved with the +.I /etc/gai.conf +file. +.PP +Each line in the configuration file consists of a keyword and its parameters. +White spaces in any place are ignored. +Lines starting with \[aq]#\[aq] are comments and are ignored. +.PP +The keywords currently recognized are: +.TP +\fBlabel\fR \fInetmask\fR \fIprecedence\fR +The value is added to the label table used in the RFC\ 3484 sorting. +If any \fBlabel\fR definition is present in the configuration file, +the default table is not used. +All the label definitions +of the default table which are to be maintained have to be duplicated. +Following the keyword, +the line has to contain a network mask and a precedence value. +.TP +\fBprecedence\fR \fInetmask\fR \fIprecedence\fR +This keyword is similar to \fBlabel\fR, but instead the value is added +to the precedence table as specified in RFC\ 3484. +Once again, the +presence of a single \fBprecedence\fR line in the configuration file +causes the default table to not be used. +.TP +\fBreload\fR <\fByes\fR|\fBno\fR> +This keyword controls whether a process checks whether the configuration +file has been changed since the last time it was read. +If the value is +"\fByes\fR", the file is reread. +This might cause problems in multithreaded +applications and is generally a bad idea. +The default is "\fBno\fR". +.TP +\fBscopev4\fR \fImask\fR \fIvalue\fR +Add another rule to the RFC\ 3484 scope table for IPv4 address. +By default, the scope IDs described in section 3.2 in RFC\ 3438 are used. +Changing these defaults should hardly ever be necessary. +.SH FILES +\fI/etc/gai.conf\fR +.SH VERSIONS +The +.I gai.conf +.\" Added in 2006 +file is supported since glibc 2.5. +.SH EXAMPLES +The default table according to RFC\ 3484 would be specified with the +following configuration file: +.PP +.in +4n +.EX +label ::1/128 0 +label ::/0 1 +label 2002::/16 2 +label ::/96 3 +label ::ffff:0:0/96 4 +precedence ::1/128 50 +precedence ::/0 40 +precedence 2002::/16 30 +precedence ::/96 20 +precedence ::ffff:0:0/96 10 +.EE +.in +.\" .SH AUTHOR +.\" Ulrich Drepper <drepper@redhat.com> +.\" +.SH SEE ALSO +.BR getaddrinfo (3), +RFC\ 3484 diff --git a/man5/group.5 b/man5/group.5 new file mode 100644 index 0000000..d39f843 --- /dev/null +++ b/man5/group.5 @@ -0,0 +1,55 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sat Jul 24 17:06:03 1993 by Rik Faith (faith@cs.unc.edu) +.TH group 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +group \- user group file +.SH DESCRIPTION +The +.I /etc/group +file is a text file that defines the groups on the system. +There is one entry per line, with the following format: +.PP +.in +4n +.EX +group_name:password:GID:user_list +.EE +.in +.PP +The fields are as follows: +.TP +.I group_name +the name of the group. +.TP +.I password +the (encrypted) group password. +If this field is empty, no password is needed. +.TP +.I GID +the numeric group ID. +.TP +.I user_list +a list of the usernames that are members of this group, separated by commas. +.SH FILES +.I /etc/group +.SH BUGS +As the 4.2BSD +.BR initgroups (3) +man page says: no one seems to keep +.I /etc/group +up-to-date. +.SH SEE ALSO +.BR chgrp (1), +.BR gpasswd (1), +.BR groups (1), +.BR login (1), +.BR newgrp (1), +.BR sg (1), +.BR getgrent (3), +.BR getgrnam (3), +.BR gshadow (5), +.BR passwd (5), +.BR vigr (8) diff --git a/man5/host.conf.5 b/man5/host.conf.5 new file mode 100644 index 0000000..8f64551 --- /dev/null +++ b/man5/host.conf.5 @@ -0,0 +1,204 @@ +.\" Copyright (c) 1997 Martin Schulze (joey@infodrom.north.de) +.\" Much of the text is copied from the manpage of resolv+(8). +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" 2003-08-23 Martin Schulze <joey@infodrom.org> Updated according to glibc 2.3.2 +.TH host.conf 5 2023-03-08 "Linux man-pages 6.05.01" +.SH NAME +host.conf \- resolver configuration file +.SH DESCRIPTION +The file +.I /etc/host.conf +contains configuration information specific to the resolver library. +It should contain one configuration keyword per line, followed by +appropriate configuration information. +The following keywords are recognized: +.TP +.I trim +This keyword may be listed more than once. +Each time it should be +followed by a list of domains, separated by colons (\[aq]:\[aq]), semicolons +(\[aq];\[aq]) or commas (\[aq],\[aq]), with the leading dot. +When set, the +resolver library will automatically trim the given domain name from the +end of any hostname resolved via DNS. +This is intended for use with +local hosts and domains. +(Related note: +.I trim +will not affect hostnames gathered via NIS or the +.BR hosts (5) +file. +Care should be taken to +ensure that the first hostname for each entry in the hosts file is +fully qualified or unqualified, as appropriate for the local +installation.) +.TP +.I multi +Valid values are +.IR on " and " off . +If set to +.IR on , +the resolver library will return all valid addresses for a host that +appears in the +.I /etc/hosts +file, +instead of only the first. +This is +.I off +by default, as it may cause a substantial performance loss at sites +with large hosts files. +.TP +.I reorder +Valid values are +.IR on " and " off . +If set to +.IR on , +the resolver library +will attempt to reorder host addresses so that local addresses +(i.e., on the same subnet) are listed first when a +.BR gethostbyname (3) +is performed. +Reordering is done for all lookup methods. +The default value is +.IR off . +.SH ENVIRONMENT +The following environment variables can be used to allow users to +override the behavior which is configured in +.IR /etc/host.conf : +.TP +.B RESOLV_HOST_CONF +If set, this variable points to a file that should be read instead of +.IR /etc/host.conf . +.TP +.B RESOLV_MULTI +Overrides the +.I multi +command. +.TP +.B RESOLV_REORDER +Overrides the +.I reorder +command. +.TP +.B RESOLV_ADD_TRIM_DOMAINS +A list of domains, +separated by +colons (\[aq]:\[aq]), semicolons (\[aq];\[aq]), or commas (\[aq],\[aq]), +with the leading dot, +which will be added to the list of domains that should be trimmed. +.TP +.B RESOLV_OVERRIDE_TRIM_DOMAINS +A list of domains, +separated by +colons (\[aq]:\[aq]), semicolons (\[aq];\[aq]), or commas (\[aq],\[aq]), +with the leading dot, +which will replace the list of domains that should be trimmed. +Overrides the +.I trim +command. +.SH FILES +.TP +.I /etc/host.conf +Resolver configuration file +.TP +.I /etc/resolv.conf +Resolver configuration file +.TP +.I /etc/hosts +Local hosts database +.SH NOTES +The following differences exist compared to the original implementation. +A new command +.I spoof +and a new environment variable +.B RESOLV_SPOOF_CHECK +can take arguments like +.IR off ", " nowarn ", and " warn . +Line comments can appear anywhere and not only at the beginning of a line. +.SS Historical +The +.BR nsswitch.conf (5) +file is the modern way of controlling the order of host lookups. +.PP +In glibc 2.4 and earlier, the following keyword is recognized: +.TP +.I order +This keyword specifies how host lookups are to be performed. +It should be followed by one or more lookup methods, separated by commas. +Valid methods are +.IR bind ", " hosts ", and " nis . +.TP +.B RESOLV_SERV_ORDER +Overrides the +.I order +command. +.PP +.\" commit 7d68cdaa4f748e87ee921f587ee2d483db624b3d +Since glibc 2.0.7, and up through glibc 2.24, +the following keywords and environment variable +have been recognized but never implemented: +.TP +.I nospoof +Valid values are +.IR on " and " off . +If set to +.IR on , +the resolver library will attempt to prevent hostname spoofing to +enhance the security of +.BR rlogin " and " rsh . +It works as follows: after performing a host address lookup, +the resolver library will perform a hostname lookup for that address. +If the two hostnames +do not match, the query fails. +The default value is +.IR off . +.TP +.I spoofalert +Valid values are +.IR on " and " off . +If this option is set to +.I on +and the +.I nospoof +option is also set, +the resolver library will log a warning of the error via the +syslog facility. +The default value is +.IR off . +.TP +.I spoof +Valid values are +.IR off ", " nowarn ", and " warn . +If this option is set to +.IR off , +spoofed addresses are permitted and no warnings will be emitted +via the syslog facility. +If this option is set to +.IR warn , +the resolver library will attempt to prevent hostname spoofing to +enhance the security and log a warning of the error via the syslog +facility. +If this option is set to +.IR nowarn , +the resolver library will attempt to prevent hostname spoofing to +enhance the security but not emit warnings via the syslog facility. +Setting this option to anything else is equal to setting it to +.IR nowarn . +.TP +.B RESOLV_SPOOF_CHECK +Overrides the +.IR nospoof ", " spoofalert ", and " spoof +commands in the same way as the +.I spoof +command is parsed. +Valid values are +.IR off ", " nowarn ", and " warn . +.SH SEE ALSO +.BR gethostbyname (3), +.BR hosts (5), +.BR nsswitch.conf (5), +.BR resolv.conf (5), +.BR hostname (7), +.BR named (8) diff --git a/man5/hosts.5 b/man5/hosts.5 new file mode 100644 index 0000000..7e17814 --- /dev/null +++ b/man5/hosts.5 @@ -0,0 +1,122 @@ +.\" Copyright (c) 2000 Manoj Srivastava <srivasta@debian.org> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Minor polishing, aeb +.\" Modified, 2002-06-16, Mike Coleman +.\" +.TH hosts 5 2023-05-03 "Linux man-pages 6.05.01" +.SH NAME +hosts \- static table lookup for hostnames +.SH SYNOPSIS +.nf +.B /etc/hosts +.fi +.SH DESCRIPTION +This manual page describes the format of the +.I /etc/hosts +file. +This file is a simple text file that associates IP addresses +with hostnames, one line per IP address. +For each host a single +line should be present with the following information: +.RS +.PP +IP_address canonical_hostname [aliases...] +.RE +.PP +The IP address can conform to either IPv4 or IPv6. +Fields of the entry are separated by any number of blanks and/or +tab characters. +Text from a "#" character until the end of the line is +a comment, and is ignored. +Host names may contain only alphanumeric +characters, minus signs ("\-"), and periods ("."). +They must begin with an +alphabetic character and end with an alphanumeric character. +Optional aliases provide for name changes, alternate spellings, +shorter hostnames, or generic hostnames (for example, +.IR localhost ). +If required, a host may have two separate entries in this file; +one for each version of the Internet Protocol (IPv4 and IPv6). +.PP +The Berkeley Internet Name Domain (BIND) Server implements the +Internet name server for UNIX systems. +It augments or replaces the +.I /etc/hosts +file or hostname lookup, and frees a host from relying on +.I /etc/hosts +being up to date and complete. +.PP +In modern systems, even though the host table has been superseded by +DNS, it is still widely used for: +.TP +.B bootstrapping +Most systems have a small host table containing the name and address +information for important hosts on the local network. +This is useful +when DNS is not running, for example during system bootup. +.TP +.B NIS +Sites that use NIS use the host table as input to the NIS host +database. +Even though NIS can be used with DNS, most NIS sites still +use the host table with an entry for all local hosts as a backup. +.TP +.B isolated nodes +Very small sites that are isolated from the network use the host table +instead of DNS. +If the local information rarely changes, and the +network is not connected to the Internet, DNS offers little +advantage. +.SH FILES +.I /etc/hosts +.SH NOTES +Modifications to this file normally take effect immediately, +except in cases where the file is cached by applications. +.SS Historical notes +RFC\ 952 gave the original format for the host table, though it has +since changed. +.PP +Before the advent of DNS, the host table was the only way of resolving +hostnames on the fledgling Internet. +Indeed, this file could be +created from the official host data base maintained at the Network +Information Control Center (NIC), though local changes were often +required to bring it up to date regarding unofficial aliases and/or +unknown hosts. +The NIC no longer maintains the hosts.txt files, +though looking around at the time of writing (circa 2000), there are +historical hosts.txt files on the WWW. +I just found three, from 92, +94, and 95. +.SH EXAMPLES +.EX +# The following lines are desirable for IPv4 capable hosts +127.0.0.1 localhost +\& +# 127.0.1.1 is often used for the FQDN of the machine +127.0.1.1 thishost.example.org thishost +192.168.1.10 foo.example.org foo +192.168.1.13 bar.example.org bar +146.82.138.7 master.debian.org master +209.237.226.90 www.opensource.org +\& +# The following lines are desirable for IPv6 capable hosts +::1 localhost ip6\-localhost ip6\-loopback +ff02::1 ip6\-allnodes +ff02::2 ip6\-allrouters +.EE +.SH SEE ALSO +.BR hostname (1), +.BR resolver (3), +.BR host.conf (5), +.BR resolv.conf (5), +.BR resolver (5), +.BR hostname (7), +.BR named (8) +.PP +Internet RFC\ 952 +.\" .SH AUTHOR +.\" This manual page was written by Manoj Srivastava <srivasta@debian.org>, +.\" for the Debian GNU/Linux system. diff --git a/man5/hosts.equiv.5 b/man5/hosts.equiv.5 new file mode 100644 index 0000000..a9521da --- /dev/null +++ b/man5/hosts.equiv.5 @@ -0,0 +1,212 @@ +.\" Copyright (c) 1995 Peter Tobias <tobias@et-inf.fho-emden.de> +.\" +.\" SPDX-License-Identifier: GPL-1.0-or-later +.TH hosts.equiv 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +hosts.equiv \- list of hosts and users that are granted "trusted" +.B r +command access to your system +.SH DESCRIPTION +The file +.I /etc/hosts.equiv +allows or denies hosts and users to use +the \fBr\fP-commands (e.g., +.BR rlogin , +.BR rsh , +or +.BR rcp ) +without +supplying a password. +.PP +The file uses the following format: +.TP +\fI+|[\-]hostname|+@netgroup|\-@netgroup\fP \fI[+|[\-]username|+@netgroup|\-@netgroup]\fP +.PP +The +.I hostname +is the name of a host which is logically equivalent +to the local host. +Users logged into that host are allowed to access +like-named user accounts on the local host without supplying a password. +The +.I hostname +may be (optionally) preceded by a plus (+) sign. +If the plus sign is used alone, it allows any host to access your system. +You can explicitly deny access to a host by preceding the +.I hostname +by a minus (\-) sign. +Users from that host must always supply additional credentials, +including possibly a password. +For security reasons you should always +use the FQDN of the hostname and not the short hostname. +.PP +The +.I username +entry grants a specific user access to all user +accounts (except root) without supplying a password. +That means the +user is NOT restricted to like-named accounts. +The +.I username +may +be (optionally) preceded by a plus (+) sign. +You can also explicitly +deny access to a specific user by preceding the +.I username +with +a minus (\-) sign. +This says that the user is not trusted no matter +what other entries for that host exist. +.PP +Netgroups can be specified by preceding the netgroup by an @ sign. +.PP +Be extremely careful when using the plus (+) sign. +A simple typographical +error could result in a standalone plus sign. +A standalone plus sign is +a wildcard character that means "any host"! +.SH FILES +.I /etc/hosts.equiv +.SH NOTES +Some systems will honor the contents of this file only when it has owner +root and no write permission for anybody else. +Some exceptionally +paranoid systems even require that there be no other hard links to the file. +.PP +Modern systems use the Pluggable Authentication Modules library (PAM). +With PAM a standalone plus sign is considered a wildcard +character which means "any host" only when the word +.I promiscuous +is added to the auth component line in your PAM file for +the particular service +.RB "(e.g., " rlogin ). +.SH EXAMPLES +Below are some example +.I /etc/host.equiv +or +.I \[ti]/.rhosts +files. +.PP +Allow any user to log in from any host: +.PP +.in +4n +.EX ++ +.EE +.in +.PP +Allow any user from +.I host +with a matching local account to log in: +.PP +.in +4n +.EX +host +.EE +.in +.PP +Note: the use of +.I +host +is never a valid syntax, +including attempting to specify that any user from the host is allowed. +.PP +Allow any user from +.I host +to log in: +.PP +.in +4n +.EX +host + +.EE +.in +.PP +Note: this is distinct from the previous example +since it does not require a matching local account. +.PP +Allow +.I user +from +.I host +to log in as any non-root user: +.PP +.in +4n +.EX +host user +.EE +.in +.PP +Allow all users with matching local accounts from +.I host +to log in except for +.IR baduser : +.PP +.in +4n +.EX +host \-baduser +host +.EE +.in +.PP +Deny all users from +.IR host : +.PP +.in +4n +.EX +\-host +.EE +.in +.PP +Note: the use of +.I "\-host\ \-user" +is never a valid syntax, +including attempting to specify that a particular user from the host +is not trusted. +.PP +Allow all users with matching local accounts on all hosts in a +.IR netgroup : +.PP +.in +4n +.EX ++@netgroup +.EE +.in +.PP +Disallow all users on all hosts in a +.IR netgroup : +.PP +.in +4n +.EX +\-@netgroup +.EE +.in +.PP +Allow all users in a +.I netgroup +to log in from +.I host +as any non-root user: +.PP +.in +4n +.EX +host +@netgroup +.EE +.in +.PP +Allow all users with matching local accounts on all hosts in a +.I netgroup +except +.IR baduser : +.PP +.in +4n +.EX ++@netgroup \-baduser ++@netgroup +.EE +.in +.PP +Note: the deny statements must always precede the allow statements because +the file is processed sequentially until the first matching rule is found. +.SH SEE ALSO +.BR rhosts (5), +.BR rlogind (8), +.BR rshd (8) diff --git a/man5/intro.5 b/man5/intro.5 new file mode 100644 index 0000000..d30e194 --- /dev/null +++ b/man5/intro.5 @@ -0,0 +1,23 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sat Jul 24 17:06:52 1993 by Rik Faith (faith@cs.unc.edu) +.\" Modified Sun Jan 14 00:34:09 1996 by Andries Brouwer (aeb@cwi.nl) +.TH intro 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +intro \- introduction to file formats and filesystems +.SH DESCRIPTION +Section 5 of the manual describes various file formats, +as well as the corresponding C structures, if any. +.PP +In addition, +this section contains a number of pages that document various filesystems. +.SH NOTES +.SS Authors and copyright conditions +Look at the header of the manual page source for the author(s) and copyright +conditions. +Note that these can be different from page to page! +.SH SEE ALSO +.BR standards (7) diff --git a/man5/issue.5 b/man5/issue.5 new file mode 100644 index 0000000..98dfe68 --- /dev/null +++ b/man5/issue.5 @@ -0,0 +1,24 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sun Jul 25 11:06:22 1993 by Rik Faith <faith@cs.unc.edu> +.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond <esr@thyrsus.com> +.TH issue 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +issue \- prelogin message and identification file +.SH DESCRIPTION +.I /etc/issue +is a text file which contains a message or +system identification to be printed before the login prompt. +It may contain various \fB@\fP\fIchar\fP and \fB\e\fP\fIchar\fP +sequences, if supported by the +.BR getty -type +program employed on the system. +.SH FILES +.I /etc/issue +.SH SEE ALSO +.BR motd (5), +.BR agetty (8), +.BR mingetty (8) diff --git a/man5/locale.5 b/man5/locale.5 new file mode 100644 index 0000000..051e5ed --- /dev/null +++ b/man5/locale.5 @@ -0,0 +1,1316 @@ +.\" Copyright (C) 1994 Jochen Hein (Hein@Student.TU-Clausthal.de) +.\" Copyright (C) 2008 Petr Baudis (pasky@suse.cz) +.\" Copyright (C) 2014 Michael Kerrisk <mtk@manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" 2008-06-17 Petr Baudis <pasky@suse.cz> +.\" LC_TIME: Describe first_weekday and first_workday +.\" +.TH locale 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +locale \- describes a locale definition file +.SH DESCRIPTION +The +.B locale +definition file contains all the information that the +.BR localedef (1) +command needs to convert it into the binary locale database. +.PP +The definition files consist of sections which each describe a +locale category in detail. +See +.BR locale (7) +for additional details for these categories. +.SS Syntax +The locale definition file starts with a header that may consist +of the following keywords: +.TP +.I escape_char +is followed by a character that should be used as the +escape-character for the rest of the file to mark characters that +should be interpreted in a special way. +It defaults to the backslash (\e). +.TP +.I comment_char +is followed by a character that will be used as the +comment-character for the rest of the file. +It defaults to the number sign (#). +.PP +The locale definition has one part for each locale category. +Each part can be copied from another existing locale or +can be defined from scratch. +If the category should be copied, +the only valid keyword in the definition is +.I copy +followed by the name of the locale in double quotes which should be +copied. +The exceptions for this rule are +.B LC_COLLATE +and +.B LC_CTYPE +where a +.I copy +statement can be followed by locale-specific rules and selected overrides. +.PP +When defining a locale or a category from scratch, an existing system- +provided locale definition file should be used as a reference to follow +common glibc conventions. +.SS Locale category sections +The following category sections are defined by POSIX: +.IP \[bu] 3 +.B LC_CTYPE +.IP \[bu] +.B LC_COLLATE +.IP \[bu] +.B LC_MESSAGES +.IP \[bu] +.B LC_MONETARY +.IP \[bu] +.B LC_NUMERIC +.IP \[bu] +.B LC_TIME +.PP +In addition, since glibc 2.2, +the GNU C library supports the following nonstandard categories: +.IP \[bu] 3 +.B LC_ADDRESS +.IP \[bu] +.B LC_IDENTIFICATION +.IP \[bu] +.B LC_MEASUREMENT +.IP \[bu] +.B LC_NAME +.IP \[bu] +.B LC_PAPER +.IP \[bu] +.B LC_TELEPHONE +.PP +See +.BR locale (7) +for a more detailed description of each category. +.SS LC_ADDRESS +The definition starts with the string +.I LC_ADDRESS +in the first column. +.PP +The following keywords are allowed: +.TP +.I postal_fmt +followed by a string containing field descriptors that define +the format used for postal addresses in the locale. +The following field descriptors are recognized: +.RS +.TP +%n +Person's name, possibly constructed with the +.B LC_NAME +.I name_fmt +keyword (since glibc 2.24). +.TP 4 +%a +Care of person, or organization. +.TP +%f +Firm name. +.TP +%d +Department name. +.TP +%b +Building name. +.TP +%s +Street or block (e.g., Japanese) name. +.TP +%h +House number or designation. +.TP +%N +Insert an end-of-line if the previous descriptor's value was not an empty +string; otherwise ignore. +.TP +%t +Insert a space if the previous descriptor's value was not an empty string; +otherwise ignore. +.TP +%r +Room number, door designation. +.TP +%e +Floor number. +.TP +%C +Country designation, from the +.I country_post +keyword. +.TP +%l +Local township within town or city (since glibc 2.24). +.TP +%z +Zip number, postal code. +.TP +%T +Town, city. +.TP +%S +State, province, or prefecture. +.TP +%c +Country, as taken from data record. +.PP +Each field descriptor may have an \[aq]R\[aq] after +the \[aq]%\[aq] to specify that the +information is taken from a Romanized version string of the +entity. +.RE +.TP +.I country_name +followed by the country name in the language of the current document +(e.g., "Deutschland" for the +.B de_DE +locale). +.TP +.I country_post +followed by the abbreviation of the country (see CERT_MAILCODES). +.TP +.I country_ab2 +followed by the two-letter abbreviation of the country (ISO 3166). +.TP +.I country_ab3 +followed by the three-letter abbreviation of the country (ISO 3166). +.TP +.I country_num +followed by the numeric country code (ISO 3166). +.TP +.I country_car +followed by the international license plate country code. +.TP +.I country_isbn +followed by the ISBN code (for books). +.TP +.I lang_name +followed by the language name in the language of the current document. +.TP +.I lang_ab +followed by the two-letter abbreviation of the language (ISO 639). +.TP +.I lang_term +followed by the three-letter abbreviation of the language (ISO 639-2/T). +.TP +.I lang_lib +followed by the three-letter abbreviation of the language for library +use (ISO 639-2/B). +Applications should in general prefer +.I lang_term +over +.IR lang_lib . +.PP +The +.B LC_ADDRESS +definition ends with the string +.IR "END LC_ADDRESS" . +.SS LC_CTYPE +The definition starts with the string +.I LC_CTYPE +in the first column. +.PP +The following keywords are allowed: +.TP +.I upper +followed by a list of uppercase letters. +The letters +.B A +through +.B Z +are included automatically. +Characters also specified as +.BR cntrl , +.BR digit , +.BR punct , +or +.B space +are not allowed. +.TP +.I lower +followed by a list of lowercase letters. +The letters +.B a +through +.B z +are included automatically. +Characters also specified as +.BR cntrl , +.BR digit , +.BR punct , +or +.B space +are not allowed. +.TP +.I alpha +followed by a list of letters. +All character specified as either +.B upper +or +.B lower +are automatically included. +Characters also specified as +.BR cntrl , +.BR digit , +.BR punct , +or +.B space +are not allowed. +.TP +.I digit +followed by the characters classified as numeric digits. +Only the +digits +.B 0 +through +.B 9 +are allowed. +They are included by default in this class. +.TP +.I space +followed by a list of characters defined as white-space +characters. +Characters also specified as +.BR upper , +.BR lower , +.BR alpha , +.BR digit , +.BR graph , +or +.B xdigit +are not allowed. +The characters +.BR <space> , +.BR <form-feed> , +.BR <newline> , +.BR <carriage-return> , +.BR <tab> , +and +.B <vertical-tab> +are automatically included. +.TP +.I cntrl +followed by a list of control characters. +Characters also specified as +.BR upper , +.BR lower , +.BR alpha , +.BR digit , +.BR punct , +.BR graph , +.BR print , +or +.B xdigit +are not allowed. +.TP +.I punct +followed by a list of punctuation characters. +Characters also +specified as +.BR upper , +.BR lower , +.BR alpha , +.BR digit , +.BR cntrl , +.BR xdigit , +or the +.B <space> +character are not allowed. +.TP +.I graph +followed by a list of printable characters, not including the +.B <space> +character. +The characters defined as +.BR upper , +.BR lower , +.BR alpha , +.BR digit , +.BR xdigit , +and +.B punct +are automatically included. +Characters also specified as +.B cntrl +are not allowed. +.TP +.I print +followed by a list of printable characters, including the +.B <space> +character. +The characters defined as +.BR upper , +.BR lower , +.BR alpha , +.BR digit , +.BR xdigit , +.BR punct , +and the +.B <space> +character are automatically included. +Characters also specified as +.B cntrl +are not allowed. +.TP +.I xdigit +followed by a list of characters classified as hexadecimal +digits. +The decimal digits must be included followed by one or +more set of six characters in ascending order. +The following +characters are included by default: +.B 0 +through +.BR 9 , +.B a +through +.BR f , +.B A +through +.BR F . +.TP +.I blank +followed by a list of characters classified as +.BR blank . +The characters +.B <space> +and +.B <tab> +are automatically included. +.TP +.I charclass +followed by a list of locale-specific character class names +which are then to be defined in the locale. +.TP +.I toupper +followed by a list of mappings from lowercase to uppercase +letters. +Each mapping is a pair of a lowercase and an uppercase letter +separated with a +.B , +and enclosed in parentheses. +.TP +.I tolower +followed by a list of mappings from uppercase to lowercase +letters. +If the keyword tolower is not present, the reverse of the +toupper list is used. +.TP +.I map totitle +followed by a list of mapping pairs of +characters and letters +to be used in titles (headings). +.TP +.I class +followed by a locale-specific character class definition, +starting with the class name followed by the characters +belonging to the class. +.TP +.I charconv +followed by a list of locale-specific character mapping names +which are then to be defined in the locale. +.TP +.I outdigit +followed by a list of alternate output digits for the locale. +.TP +.I map to_inpunct +followed by a list of mapping pairs of +alternate digits and separators +for input digits for the locale. +.TP +.I map to_outpunct +followed by a list of mapping pairs of +alternate separators +for output for the locale. +.TP +.I translit_start +marks the start of the transliteration rules section. +The section can contain the +.I include +keyword in the beginning followed by +locale-specific rules and overrides. +Any rule specified in the locale file +will override any rule +copied or included from other files. +In case of duplicate rule definitions in the locale file, +only the first rule is used. +.IP +A transliteration rule consist of a character to be transliterated +followed by a list of transliteration targets separated by semicolons. +The first target which can be presented in the target character set +is used, if none of them can be used the +.I default_missing +character will be used instead. +.TP +.I include +in the transliteration rules section includes +a transliteration rule file +(and optionally a repertoire map file). +.TP +.I default_missing +in the transliteration rules section +defines the default character to be used for +transliteration where none of the targets cannot be presented +in the target character set. +.TP +.I translit_end +marks the end of the transliteration rules. +.PP +The +.B LC_CTYPE +definition ends with the string +.IR "END LC_CTYPE" . +.SS LC_COLLATE +Note that glibc does not support all POSIX-defined options, +only the options described below are supported (as of glibc 2.23). +.PP +The definition starts with the string +.I LC_COLLATE +in the first column. +.PP +The following keywords are allowed: +.TP +.I coll_weight_max +followed by the number representing used collation levels. +This keyword is recognized but ignored by glibc. +.TP +.I collating\-element +followed by the definition of a collating-element symbol +representing a multicharacter collating element. +.TP +.I collating\-symbol +followed by the definition of a collating symbol +that can be used in collation order statements. +.TP +.I define +followed by +.B string +to be evaluated in an +.I ifdef +.B string +/ +.I else +/ +.I endif +construct. +.TP +.I reorder\-after +followed by a redefinition of a collation rule. +.TP +.I reorder\-end +marks the end of the redefinition of a collation rule. +.TP +.I reorde\r-sections\-after +followed by a script name to reorder listed scripts after. +.TP +.I reorder\-sections\-end +marks the end of the reordering of sections. +.TP +.I script +followed by a declaration of a script. +.TP +.I symbol\-equivalence +followed by a collating-symbol to be equivalent to another defined +collating-symbol. +.PP +The collation rule definition starts with a line: +.TP +.I order_start +followed by a list of keywords chosen from +.BR forward , +.BR backward , +or +.BR position . +The order definition consists of lines that describe the collation +order and is terminated with the keyword +.IR order_end . +.PP +The +.B LC_COLLATE +definition ends with the string +.IR "END LC_COLLATE" . +.SS LC_IDENTIFICATION +The definition starts with the string +.I LC_IDENTIFICATION +in the first column. +.PP +The following keywords are allowed: +.TP +.I title +followed by the title of the locale document +(e.g., "Maori language locale for New Zealand"). +.TP +.I source +followed by the name of the organization that maintains this document. +.TP +.I address +followed by the address of the organization that maintains this document. +.TP +.I contact +followed by the name of the contact person at +the organization that maintains this document. +.TP +.I email +followed by the email address of the person or +organization that maintains this document. +.TP +.I tel +followed by the telephone number (in international format) +of the organization that maintains this document. +As of glibc 2.24, this keyword is deprecated in favor of +other contact methods. +.TP +.I fax +followed by the fax number (in international format) +of the organization that maintains this document. +As of glibc 2.24, this keyword is deprecated in favor of +other contact methods. +.TP +.I language +followed by the name of the language to which this document applies. +.TP +.I territory +followed by the name of the country/geographic extent +to which this document applies. +.TP +.I audience +followed by a description of the audience for which this document is +intended. +.TP +.I application +followed by a description of any special application +for which this document is intended. +.TP +.I abbreviation +followed by the short name for provider of the source of this document. +.TP +.I revision +followed by the revision number of this document. +.TP +.I date +followed by the revision date of this document. +.PP +In addition, for each of the categories defined by the document, +there should be a line starting with the keyword +.IR category , +followed by: +.IP (1) 5 +a string that identifies this locale category definition, +.IP (2) +a semicolon, and +.IP (3) +one of the +.B LC_* +identifiers. +.PP +The +.B LC_IDENTIFICATION +definition ends with the string +.IR "END LC_IDENTIFICATION" . +.SS LC_MESSAGES +The definition starts with the string +.I LC_MESSAGES +in the first column. +.PP +The following keywords are allowed: +.TP +.I yesexpr +followed by a regular expression that describes possible +yes-responses. +.TP +.I noexpr +followed by a regular expression that describes possible +no-responses. +.TP +.I yesstr +followed by the output string corresponding to "yes". +.TP +.I nostr +followed by the output string corresponding to "no". +.PP +The +.B LC_MESSAGES +definition ends with the string +.IR "END LC_MESSAGES" . +.SS LC_MEASUREMENT +The definition starts with the string +.I LC_MEASUREMENT +in the first column. +.PP +The following keywords are allowed: +.TP +.I measurement +followed by number identifying the standard used for measurement. +The following values are recognized: +.RS +.TP 4 +.B 1 +Metric. +.TP +.B 2 +US customary measurements. +.RE +.PP +The +.B LC_MEASUREMENT +definition ends with the string +.IR "END LC_MEASUREMENT" . +.SS LC_MONETARY +The definition starts with the string +.I LC_MONETARY +in the first column. +.PP +The following keywords are allowed: +.TP +.I int_curr_symbol +followed by the international currency symbol. +This must be a +4-character string containing the international currency symbol as +defined by the ISO 4217 standard (three characters) followed by a +separator. +.TP +.I currency_symbol +followed by the local currency symbol. +.TP +.I mon_decimal_point +followed by the single-character string that will be used as the +decimal delimiter when formatting monetary quantities. +.TP +.I mon_thousands_sep +followed by the single-character string that will be used as a group +separator when formatting monetary quantities. +.TP +.I mon_grouping +followed by a sequence of integers separated by semicolons that +describe the formatting of monetary quantities. +See +.I grouping +below for details. +.TP +.I positive_sign +followed by a string that is used to indicate a positive sign for +monetary quantities. +.TP +.I negative_sign +followed by a string that is used to indicate a negative sign for +monetary quantities. +.TP +.I int_frac_digits +followed by the number of fractional digits that should be used when +formatting with the +.IR int_curr_symbol . +.TP +.I frac_digits +followed by the number of fractional digits that should be used when +formatting with the +.IR currency_symbol . +.TP +.I p_cs_precedes +followed by an integer that indicates the placement of +.I currency_symbol +for a nonnegative formatted monetary quantity: +.RS +.TP 4 +.B 0 +the symbol succeeds the value. +.TP +.B 1 +the symbol precedes the value. +.RE +.TP +.I p_sep_by_space +followed by an integer that indicates the separation of +.IR currency_symbol , +the sign string, and the value for a nonnegative formatted monetary quantity. +The following values are recognized: +.RS +.TP 4 +.B 0 +No space separates the currency symbol and the value. +.TP +.B 1 +If the currency symbol and the sign string are adjacent, +a space separates them from the value; +otherwise a space separates the currency symbol and the value. +.TP +.B 2 +If the currency symbol and the sign string are adjacent, +a space separates them from the value; +otherwise a space separates the sign string and the value. +.RE +.TP +.I n_cs_precedes +followed by an integer that indicates the placement of +.I currency_symbol +for a negative formatted monetary quantity. +The same values are recognized as for +.IR p_cs_precedes . +.TP +.I n_sep_by_space +followed by an integer that indicates the separation of +.IR currency_symbol , +the sign string, and the value for a negative formatted monetary quantity. +The same values are recognized as for +.IR p_sep_by_space . +.TP +.I p_sign_posn +followed by an integer that indicates where the +.I positive_sign +should be placed for a nonnegative monetary quantity: +.RS +.TP 4 +.B 0 +Parentheses enclose the quantity and the +.I currency_symbol +or +.IR int_curr_symbol . +.TP +.B 1 +The sign string precedes the quantity and the +.I currency_symbol +or the +.IR int_curr_symbol . +.TP +.B 2 +The sign string succeeds the quantity and the +.I currency_symbol +or the +.IR int_curr_symbol . +.TP +.B 3 +The sign string precedes the +.I currency_symbol +or the +.IR int_curr_symbol . +.TP +.B 4 +The sign string succeeds the +.I currency_symbol +or the +.IR int_curr_symbol . +.RE +.TP +.I n_sign_posn +followed by an integer that indicates where the +.I negative_sign +should be placed for a negative monetary quantity. +The same values are recognized as for +.IR p_sign_posn . +.TP +.I int_p_cs_precedes +followed by an integer that indicates the placement of +.I int_curr_symbol +for a nonnegative internationally formatted monetary quantity. +The same values are recognized as for +.IR p_cs_precedes . +.TP +.I int_n_cs_precedes +followed by an integer that indicates the placement of +.I int_curr_symbol +for a negative internationally formatted monetary quantity. +The same values are recognized as for +.IR p_cs_precedes . +.TP +.I int_p_sep_by_space +followed by an integer that indicates the separation of +.IR int_curr_symbol , +the sign string, +and the value for a nonnegative internationally formatted monetary quantity. +The same values are recognized as for +.IR p_sep_by_space . +.TP +.I int_n_sep_by_space +followed by an integer that indicates the separation of +.IR int_curr_symbol , +the sign string, +and the value for a negative internationally formatted monetary quantity. +The same values are recognized as for +.IR p_sep_by_space . +.TP +.I int_p_sign_posn +followed by an integer that indicates where the +.I positive_sign +should be placed for a nonnegative +internationally formatted monetary quantity. +The same values are recognized as for +.IR p_sign_posn . +.TP +.I int_n_sign_posn +followed by an integer that indicates where the +.I negative_sign +should be placed for a negative +internationally formatted monetary quantity. +The same values are recognized as for +.IR p_sign_posn . +.PP +The +.B LC_MONETARY +definition ends with the string +.IR "END LC_MONETARY" . +.SS LC_NAME +The definition starts with the string +.I LC_NAME +in the first column. +.PP +Various keywords are allowed, but only +.I name_fmt +is mandatory. +Other keywords are needed only if there is common convention to +use the corresponding salutation in this locale. +The allowed keywords are as follows: +.TP +.I name_fmt +followed by a string containing field descriptors that define +the format used for names in the locale. +The following field descriptors are recognized: +.RS +.TP 4 +%f +Family name(s). +.TP +%F +Family names in uppercase. +.TP +%g +First given name. +.TP +%G +First given initial. +.TP +%l +First given name with Latin letters. +.TP +%o +Other shorter name. +.TP +%m +Additional given name(s). +.TP +%M +Initials for additional given name(s). +.TP +%p +Profession. +.TP +%s +Salutation, such as "Doctor". +.TP +%S +Abbreviated salutation, such as "Mr." or "Dr.". +.TP +%d +Salutation, using the FDCC-sets conventions. +.\" 1 for the name_gen +.\" In glibc 2.19, %d1 is used in only: +.\" /home/mtk/ARCHIVE/GLIBC/glibc-2.19/localedata/locales/bem_ZM +.\" /home/mtk/ARCHIVE/GLIBC/glibc-2.19/localedata/locales/zh_HK +.\" In glibc 2.19, %d[2-5] appear to be not used at all +.\" 2 for name_mr +.\" 3 for name_mrs +.\" 4 for name_miss +.\" 5 for name_ms +.TP +%t +If the preceding field descriptor resulted in an empty string, +then the empty string, otherwise a space character. +.RE +.TP +.I name_gen +followed by the general salutation for any gender. +.TP +.I name_mr +followed by the salutation for men. +.TP +.I name_mrs +followed by the salutation for married women. +.TP +.I name_miss +followed by the salutation for unmarried women. +.TP +.I name_ms +followed by the salutation valid for all women. +.PP +The +.B LC_NAME +definition ends with the string +.IR "END LC_NAME" . +.SS LC_NUMERIC +The definition starts with the string +.I LC_NUMERIC +in the first column. +.PP +The following keywords are allowed: +.TP +.I decimal_point +followed by the single-character string that will be used as the +decimal delimiter when formatting numeric quantities. +.TP +.I thousands_sep +followed by the single-character string that will be used as a group +separator when formatting numeric quantities. +.TP +.I grouping +followed by a sequence of integers separated by semicolons +that describe the formatting of numeric quantities. +.IP +Each integer specifies the number of digits in a group. +The first integer defines the size of the group immediately +to the left of the decimal delimiter. +Subsequent integers define succeeding groups to the +left of the previous group. +If the last integer is not \-1, then the size of the previous group +(if any) is repeatedly used for the remainder of the digits. +If the last integer is \-1, then no further grouping is performed. +.PP +The +.B LC_NUMERIC +definition ends with the string +.IR "END LC_NUMERIC" . +.SS LC_PAPER +The definition starts with the string +.I LC_PAPER +in the first column. +.PP +The following keywords are allowed: +.TP +.I height +followed by the height, in millimeters, of the standard paper format. +.TP +.I width +followed by the width, in millimeters, of the standard paper format. +.PP +The +.B LC_PAPER +definition ends with the string +.IR "END LC_PAPER" . +.SS LC_TELEPHONE +The definition starts with the string +.I LC_TELEPHONE +in the first column. +.PP +The following keywords are allowed: +.TP +.I tel_int_fmt +followed by a string that contains field descriptors that identify +the format used to dial international numbers. +The following field descriptors are recognized: +.RS +.TP 4 +%a +Area code without nationwide prefix (the prefix is often "00"). +.TP +%A +Area code including nationwide prefix. +.TP +%l +Local number (within area code). +.TP +%e +Extension (to local number). +.TP +%c +Country code. +.TP +%C +Alternate carrier service code used for dialing abroad. +.TP +%t +If the preceding field descriptor resulted in an empty string, +then the empty string, otherwise a space character. +.RE +.TP +.I tel_dom_fmt +followed by a string that contains field descriptors that identify +the format used to dial domestic numbers. +The recognized field descriptors are the same as for +.IR tel_int_fmt . +.TP +.I int_select +followed by the prefix used to call international phone numbers. +.TP +.I int_prefix +followed by the prefix used from other countries to dial this country. +.PP +The +.B LC_TELEPHONE +definition ends with the string +.IR "END LC_TELEPHONE" . +.SS LC_TIME +The definition starts with the string +.I LC_TIME +in the first column. +.PP +The following keywords are allowed: +.TP +.I abday +followed by a list of abbreviated names of the days of the week. +The list starts with the first day of the week +as specified by +.I week +(Sunday by default). +See NOTES. +.TP +.I day +followed by a list of names of the days of the week. +The list starts with the first day of the week +as specified by +.I week +(Sunday by default). +See NOTES. +.TP +.I abmon +followed by a list of abbreviated month names. +.TP +.I mon +followed by a list of month names. +.TP +.I d_t_fmt +followed by the appropriate date and time format +(for syntax, see +.BR strftime (3)). +.TP +.I d_fmt +followed by the appropriate date format +(for syntax, see +.BR strftime (3)). +.TP +.I t_fmt +followed by the appropriate time format +(for syntax, see +.BR strftime (3)). +.TP +.I am_pm +followed by the appropriate representation of the +.B am +and +.B pm +strings. +This should be left empty for locales not using AM/PM convention. +.TP +.I t_fmt_ampm +followed by the appropriate time format +(for syntax, see +.BR strftime (3)) +when using 12h clock format. +This should be left empty for locales not using AM/PM convention. +.TP +.I era +followed by semicolon-separated strings that define how years are +counted and displayed for each era in the locale. +Each string has the following format: +.RS +.PP +.IR direction ":" offset ":" start_date ":" end_date ":" era_name ":" era_format +.PP +The fields are to be defined as follows: +.TP 4 +.I direction +Either +.B + +or +.BR \- . +.B + +means the years closer to +.I start_date +have lower numbers than years closer to +.IR end_date . +.B \- +means the opposite. +.TP +.I offset +The number of the year closest to +.I start_date +in the era, corresponding to the +.I %Ey +descriptor (see +.BR strptime (3)). +.TP +.I start_date +The start of the era in the form of +.IR yyyy/mm/dd . +Years prior AD 1 are represented as negative numbers. +.TP +.I end_date +The end of the era in the form of +.IR yyyy/mm/dd , +or one of the two special values of +.B \-* +or +.BR +* . +.B \-* +means the ending date is the beginning of time. +.B +* +means the ending date is the end of time. +.TP +.I era_name +The name of the era corresponding to the +.I %EC +descriptor (see +.BR strptime (3)). +.TP +.I era_format +The format of the year in the era corresponding to the +.I %EY +descriptor (see +.BR strptime (3)). +.RE +.TP +.I era_d_fmt +followed by the format of the date in alternative era notation, +corresponding to the +.I %Ex +descriptor (see +.BR strptime (3)). +.TP +.I era_t_fmt +followed by the format of the time in alternative era notation, +corresponding to the +.I %EX +descriptor (see +.BR strptime (3)). +.TP +.I era_d_t_fmt +followed by the format of the date and time in alternative era notation, +corresponding to the +.I %Ec +descriptor (see +.BR strptime (3)). +.TP +.I alt_digits +followed by the alternative digits used for date and time in the locale. +.TP +.I week +followed by a list of three values separated by semicolons: +The number of days in a week (by default 7), +a date of beginning of the week (by default corresponds to Sunday), +and the minimal length of the first week in year (by default 4). +Regarding the start of the week, +.B 19971130 +shall be used for Sunday and +.B 19971201 +shall be used for Monday. +See NOTES. +.TP +.IR first_weekday " (since glibc 2.2)" +followed by the number of the day from the +.I day +list to be shown as the first day of the week in calendar applications. +The default value of +.B 1 +corresponds to either Sunday or Monday depending +on the value of the second +.I week +list item. +See NOTES. +.TP +.IR first_workday " (since glibc 2.2)" +followed by the number of the first working day from the +.I day +list. +The default value is +.BR 2 . +See NOTES. +.TP +.I cal_direction +followed by a number value that indicates the direction for the +display of calendar dates, as follows: +.RS +.TP 4 +.B 1 +Left-right from top. +.TP +.B 2 +Top-down from left. +.TP +.B 3 +Right-left from top. +.RE +.TP +.I date_fmt +followed by the appropriate date representation for +.BR date (1) +(for syntax, see +.BR strftime (3)). +.PP +The +.B LC_TIME +definition ends with the string +.IR "END LC_TIME" . +.SH FILES +.TP +.I /usr/lib/locale/locale\-archive +Usual default locale archive location. +.TP +.I /usr/share/i18n/locales +Usual default path for locale definition files. +.SH STANDARDS +POSIX.2. +.SH NOTES +The collective GNU C library community wisdom regarding +.IR abday , +.IR day , +.IR week , +.IR first_weekday , +and +.I first_workday +states at +https://sourceware.org/glibc/wiki/Locales +the following: +.IP \[bu] 3 +The value of the second +.I week +list item specifies the base of the +.I abday +and +.I day +lists. +.IP \[bu] +.I first_weekday +specifies the offset of the first day-of-week in the +.I abday +and +.I day +lists. +.IP \[bu] +For compatibility reasons, all glibc locales should set the value of the +second +.I week +list item to +.B 19971130 +(Sunday) and base the +.I abday +and +.I day +lists appropriately, and set +.I first_weekday +and +.I first_workday +to +.B 1 +or +.BR 2 , +depending on whether the week and work week actually starts on Sunday or +Monday for the locale. +.\" .SH AUTHOR +.\" Jochen Hein (Hein@Student.TU-Clausthal.de) +.SH SEE ALSO +.BR iconv (1), +.BR locale (1), +.BR localedef (1), +.BR localeconv (3), +.BR newlocale (3), +.BR setlocale (3), +.BR strftime (3), +.BR strptime (3), +.BR uselocale (3), +.BR charmap (5), +.BR charsets (7), +.BR locale (7), +.BR unicode (7), +.BR utf\-8 (7) diff --git a/man5/motd.5 b/man5/motd.5 new file mode 100644 index 0000000..b506c95 --- /dev/null +++ b/man5/motd.5 @@ -0,0 +1,25 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sat Jul 24 17:08:16 1993 by Rik Faith <faith@cs.unc.edu> +.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond <esr@thyrsus.com> +.TH motd 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +motd \- message of the day +.SH DESCRIPTION +The contents of +.I /etc/motd +are displayed by +.BR login (1) +after a successful login but just before it executes the login shell. +.PP +The abbreviation "motd" stands for "message of the day", and this file +has been traditionally used for exactly that (it requires much less disk +space than mail to all users). +.SH FILES +.I /etc/motd +.SH SEE ALSO +.BR login (1), +.BR issue (5) diff --git a/man5/networks.5 b/man5/networks.5 new file mode 100644 index 0000000..cf660e3 --- /dev/null +++ b/man5/networks.5 @@ -0,0 +1,60 @@ +.\" Copyright (c) 2001 Martin Schulze <joey@infodrom.org> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" 2008-09-04, mtk, taken from Debian downstream, with a few light edits +.\" +.TH networks 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +networks \- network name information +.SH DESCRIPTION +The file +.I /etc/networks +is a plain ASCII file that describes known DARPA networks and symbolic +names for these networks. +Each line represents a network and has the following structure: +.PP +.RS +.I name number aliases ... +.RE +.PP +where the fields are delimited by spaces or tabs. +Empty lines are ignored. +The hash character (\fB#\fP) indicates the start of a comment: +this character, and the remaining characters up to +the end of the current line, +are ignored by library functions that process the file. +.PP +The field descriptions are: +.TP +.I name +The symbolic name for the network. +Network names can contain any printable characters except +white-space characters or the comment character. +.TP +.I number +The official number for this network in numbers-and-dots notation (see +.BR inet (3)). +The trailing ".0" (for the host component of the network address) +may be omitted. +.TP +.I aliases +Optional aliases for the network. +.PP +This file is read by the +.BR route (8) +and +.BR netstat (8) +utilities. +Only Class A, B, or C networks are supported, partitioned networks +(i.e., network/26 or network/28) are not supported by this file. +.SH FILES +.TP +.I /etc/networks +The networks definition file. +.SH SEE ALSO +.BR getnetbyaddr (3), +.BR getnetbyname (3), +.BR getnetent (3), +.BR netstat (8), +.BR route (8) diff --git a/man5/nologin.5 b/man5/nologin.5 new file mode 100644 index 0000000..af006f5 --- /dev/null +++ b/man5/nologin.5 @@ -0,0 +1,22 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sun Jul 25 11:06:34 1993 by Rik Faith (faith@cs.unc.edu) +.\" Corrected Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond (esr@thyrsus.com) +.TH nologin 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +nologin \- prevent unprivileged users from logging into the system +.SH DESCRIPTION +If the file \fI/etc/nologin\fP exists and is readable, +.BR login (1) +will allow access only to root. +Other users will +be shown the contents of this file and their logins will be refused. +This provides a simple way of temporarily disabling all unprivileged logins. +.SH FILES +.I /etc/nologin +.SH SEE ALSO +.BR login (1), +.BR shutdown (8) diff --git a/man5/nscd.conf.5 b/man5/nscd.conf.5 new file mode 100644 index 0000000..041793e --- /dev/null +++ b/man5/nscd.conf.5 @@ -0,0 +1,342 @@ +.\" Copyright (c) 1999, 2000 SuSE GmbH Nuernberg, Germany +.\" Author: Thorsten Kukuk <kukuk@suse.de> +.\" Updates: Greg Banks <gbanks@linkedin.com> Copyright (c) 2021 Microsoft Corp. +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.TH nscd.conf 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +nscd.conf \- name service cache daemon configuration file +.SH DESCRIPTION +The file +.I /etc/nscd.conf +is read from +.BR nscd (8) +at startup. +Each line specifies either an attribute and a value, or an +attribute, service, and a value. +Fields are separated either by SPACE +or TAB characters. +A \[aq]#\[aq] (number sign) indicates the beginning of a +comment; following characters, up to the end of the line, +are not interpreted by nscd. +.PP +Valid services are \fIpasswd\fP, \fIgroup\fP, \fIhosts\fP, \fIservices\fP, +or \fInetgroup\fP. +.PP +.B logfile +.I debug-file-name +.RS +Specifies name of the file to which debug info should be written. +.RE +.PP +.B debug\-level +.I value +.RS +Sets the desired debug level. +0 hides debug info. +1 shows general debug info. +2 additionally shows data in cache dumps. +3 (and above) shows all debug info. +The default is 0. +.RE +.PP +.B threads +.I number +.RS +This is the initial number of threads that are started to wait for +requests. +At least five threads will always be created. +The number of threads may increase dynamically up to +.B max\-threads +in response to demand from clients, +but never decreases. +.RE +.PP +.B max\-threads +.I number +.RS +Specifies the maximum number of threads. +The default is 32. +.RE +.PP +.B server\-user +.I user +.RS +If this option is set, nscd will run as this user and not as root. +If a separate cache for every user is used (\-S parameter), this +option is ignored. +.RE +.PP +.B stat\-user +.I user +.RS +Specifies the user who is allowed to request statistics. +.RE +.PP +.B reload\-count +unlimited | +.I number +.RS +Sets a limit on the number of times a cached entry +gets reloaded without being used +before it gets removed. +The limit can take values ranging from 0 to 254; +values 255 or higher behave the same as +.BR unlimited . +Limit values can be specified in either decimal +or hexadecimal with a "0x" prefix. +The special value +.B unlimited +is case-insensitive. +The default limit is 5. +A limit of 0 turns off the reloading feature. +See NOTES below for further discussion of reloading. +.RE +.PP +.B paranoia +.I <yes|no> +.RS +Enabling paranoia mode causes nscd to restart itself periodically. +The default is no. +.RE +.PP +.B restart\-interval +.I time +.RS +Sets the restart interval to +.I time +seconds +if periodic restart is enabled by enabling +.B paranoia +mode. +The default is 3600. +.RE +.PP +.B enable\-cache +.I service +.I <yes|no> +.RS +Enables or disables the specified +.I service +cache. +The default is no. +.RE +.PP +.B positive\-time\-to\-live +.I service +.I value +.RS +Sets the TTL (time-to-live) for positive entries (successful queries) +in the specified cache for +.IR service . +.I Value +is in seconds. +Larger values increase cache hit rates and reduce mean +response times, but increase problems with cache coherence. +Note that for some name services (including specifically DNS) +the TTL returned from the name service is used and +this attribute is ignored. +.RE +.PP +.B negative\-time\-to\-live +.I service +.I value +.RS +Sets the TTL (time-to-live) for negative entries (unsuccessful queries) +in the specified cache for +.IR service . +.I Value +is in seconds. +Can result in significant performance improvements if there +are several files owned by UIDs (user IDs) not in system databases (for +example untarring the Linux kernel sources as root); should be kept small +to reduce cache coherency problems. +.RE +.PP +.B suggested\-size +.I service +.I value +.RS +This is the internal hash table size, +.I value +should remain a prime number for optimum efficiency. +The default is 211. +.RE +.PP +.B check\-files +.I service +.I <yes|no> +.RS +Enables or disables checking the file belonging to the specified +.I service +for changes. +The files are +.IR /etc/passwd , +.IR /etc/group , +.IR /etc/hosts , +.IR /etc/resolv.conf , +.IR /etc/services , +and +.IR /etc/netgroup . +The default is yes. +.RE +.PP +.B persistent +.I service +.I <yes|no> +.RS +Keep the content of the cache for +.I service +over server restarts; useful when +.B paranoia +mode is set. +The default is no. +.RE +.PP +.B shared +.I service +.I <yes|no> +.RS +The memory mapping of the nscd databases for +.I service +is shared with the clients so +that they can directly search in them instead of having to ask the +daemon over the socket each time a lookup is performed. +The default is no. +Note that a cache miss will still result in +asking the daemon over the socket. +.RE +.PP +.B max\-db\-size +.I service +.I bytes +.RS +The maximum allowable size, in bytes, of the database files for the +.IR service . +The default is 33554432. +.RE +.PP +.B auto\-propagate +.I service +.I <yes|no> +.RS +When set to +.I no +for +.I passwd +or +.I group +service, then the +.I .byname +requests are not added to +.I passwd.byuid +or +.I group.bygid +cache. +This can help with tables containing multiple records for the same ID. +The default is yes. +This option is valid only for services +.I passwd +and +.IR group . +.RE +.SH NOTES +The default values stated in this manual page originate +from the source code of +.BR nscd (8) +and are used if not overridden in the configuration file. +The default values used in the configuration file of +your distribution might differ. +.SS Reloading +.BR nscd (8) +has a feature called reloading, +whose behavior can be surprising. +.PP +Reloading is enabled when the +.B reload-count +attribute has a non-zero value. +The default value in the source code enables reloading, +although your distribution may differ. +.PP +When reloading is enabled, +positive cached entries (the results of successful queries) +do not simply expire when their TTL is up. +Instead, at the expiry time, +.B nscd +will "reload", +i.e., +re-issue to the name service the same query that created the cached entry, +to get a new value to cache. +Depending on +.I /etc/nsswitch.conf +this may mean that a DNS, LDAP, or NIS request is made. +If the new query is successful, +reloading will repeat when the new value would expire, +until +.B reload-count +reloads have happened for the entry, +and only then will it actually be removed from the cache. +A request from a client which hits the entry will +reset the reload counter on the entry. +Purging the cache using +.I nscd\~-i +overrides the reload logic and removes the entry. +.PP +Reloading has the effect of extending cache entry TTLs +without compromising on cache coherency, +at the cost of additional load on the backing name service. +Whether this is a good idea on your system depends on +details of your applications' behavior, +your name service, +and the effective TTL values of your cache entries. +Note that for some name services +(for example, DNS), +the effective TTL is the value returned from the name service and +.I not +the value of the +.B positive\-time\-to\-live +attribute. +.PP +Please consider the following advice carefully: +.IP \[bu] 3 +If your application will make a second request for the same name, +after more than 1 TTL but before +.B reload\-count +TTLs, +and is sensitive to the latency of a cache miss, +then reloading may be a good idea for you. +.IP \[bu] +If your name service is configured to return very short TTLs, +and your applications only make requests rarely under normal circumstances, +then reloading may result in additional load on your backing name service +without any benefit to applications, +which is probably a bad idea for you. +.IP \[bu] +If your name service capacity is limited, +reloading may have the surprising effect of +increasing load on your name service instead of reducing it, +and may be a bad idea for you. +.IP \[bu] +Setting +.B reload\-count +to +.B unlimited +is almost never a good idea, +as it will result in a cache that never expires entries +and puts never-ending additional load on the backing name service. +.PP +Some distributions have an init script for +.BR nscd (8) +with a +.I reload +command which uses +.I nscd\~-i +to purge the cache. +That use of the word "reload" is entirely different +from the "reloading" described here. +.SH SEE ALSO +.BR nscd (8) +.\" .SH AUTHOR +.\" .B nscd +.\" was written by Thorsten Kukuk and Ulrich Drepper. diff --git a/man5/nss.5 b/man5/nss.5 new file mode 100644 index 0000000..d53e1cd --- /dev/null +++ b/man5/nss.5 @@ -0,0 +1,101 @@ +.\" Copyright (C) 2006 Red Hat, Inc. All rights reserved. +.\" Author: Ulrich Drepper <drepper@redhat.com> +.\" +.\" SPDX-License-Identifier: GPL-2.0-only +.\" +.TH nss 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +nss \- Name Service Switch configuration file +.SH DESCRIPTION +Each call to a function which retrieves data from a system database +like the password or group database is handled by the Name Service +Switch implementation in the GNU C library. +The various services +provided are implemented by independent modules, each of which +naturally varies widely from the other. +.PP +The default implementations coming with the GNU C library are by +default conservative and do not use unsafe data. +This might be very costly in some situations, especially when the databases +are large. +Some modules allow the system administrator to request +taking shortcuts if these are known to be safe. +It is then the system administrator's responsibility to ensure the assumption +is correct. +.PP +There are other modules where the implementation changed over time. +If an implementation used to sacrifice speed for memory consumption, +it might create problems if the preference is switched. +.PP +The +.I /etc/default/nss +file contains a number of variable assignments. +Each variable controls the behavior of one or more +NSS modules. +White spaces are ignored. +Lines beginning with \[aq]#\[aq] +are treated as comments. +.PP +The variables currently recognized are: +.TP +\fBNETID_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR +If set to TRUE, the NIS backend for the +.BR initgroups (3) +function will accept the information +from the +.I netid.byname +NIS map as authoritative. +This can speed up the function significantly if the +.I group.byname +map is large. +The content of the +.I netid.byname +map is used \fBas is\fR. +The system administrator has to make sure it is correctly generated. +.TP +\fBSERVICES_AUTHORITATIVE =\fR \fITRUE\fR|\fIFALSE\fR +If set to TRUE, the NIS backend for the +.BR getservbyname (3) +and +.BR getservbyname_r (3) +functions will assume that the +.I services.byservicename +NIS map exists and is authoritative, particularly +that it contains both keys with /proto and without /proto for both +primary service names and service aliases. +The system administrator has to make sure it is correctly generated. +.TP +\fBSETENT_BATCH_READ =\fR \fITRUE\fR|\fIFALSE\fR +If set to TRUE, the NIS backend for the +.BR setpwent (3) +and +.BR setgrent (3) +functions will read the entire database at once and then +hand out the requests one by one from memory with every corresponding +.BR getpwent (3) +or +.BR getgrent (3) +call respectively. +Otherwise, each +.BR getpwent (3) +or +.BR getgrent (3) +call might result in a network communication with the server to get +the next entry. +.SH FILES +\fI/etc/default/nss\fR +.SH EXAMPLES +The default configuration corresponds to the following configuration file: +.PP +.in +4n +.EX +NETID_AUTHORITATIVE=FALSE +SERVICES_AUTHORITATIVE=FALSE +SETENT_BATCH_READ=FALSE +.EE +.in +.\" .SH AUTHOR +.\" Ulrich Drepper <drepper@redhat.com> +.\" +.SH SEE ALSO +\fInsswitch.conf\fR diff --git a/man5/nsswitch.conf.5 b/man5/nsswitch.conf.5 new file mode 100644 index 0000000..49b288e --- /dev/null +++ b/man5/nsswitch.conf.5 @@ -0,0 +1,427 @@ +.\" Copyright (c) 1998, 1999 Thorsten Kukuk (kukuk@vt.uni-paderborn.de) +.\" Copyright (c) 2011, Mark R. Bannister <cambridge@users.sourceforge.net> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.TH nsswitch.conf 5 2023-05-03 "Linux man-pages 6.05.01" +.SH NAME +nsswitch.conf \- Name Service Switch configuration file +.SH DESCRIPTION +The Name Service Switch (NSS) configuration file, +.IR /etc/nsswitch.conf , +is used by the GNU C Library and certain other applications to determine +the sources from which to obtain name-service information in +a range of categories, +and in what order. +Each category of information is identified by a database name. +.PP +The file is plain ASCII text, with columns separated by spaces or tab +characters. +The first column specifies the database name. +The remaining columns describe the order of sources to query and a +limited set of actions that can be performed by lookup result. +.PP +The following databases are understood by the GNU C Library: +.TP 12 +.B aliases +Mail aliases, used by +.BR getaliasent (3) +and related functions. +.TP +.B ethers +Ethernet numbers. +.TP +.B group +Groups of users, used by +.BR getgrent (3) +and related functions. +.TP +.B hosts +Host names and numbers, used by +.BR gethostbyname (3) +and related functions. +.TP +.B initgroups +Supplementary group access list, used by +.BR getgrouplist (3) +function. +.TP +.B netgroup +Network-wide list of hosts and users, used for access rules. +C libraries before glibc 2.1 supported netgroups only over NIS. +.TP +.B networks +Network names and numbers, used by +.BR getnetent (3) +and related functions. +.TP +.B passwd +User passwords, used by +.BR getpwent (3) +and related functions. +.TP +.B protocols +Network protocols, used by +.BR getprotoent (3) +and related functions. +.TP +.B publickey +Public and secret keys for Secure_RPC used by NFS and NIS+. +.TP +.B rpc +Remote procedure call names and numbers, used by +.BR getrpcbyname (3) +and related functions. +.TP +.B services +Network services, used by +.BR getservent (3) +and related functions. +.TP +.B shadow +Shadow user passwords, used by +.BR getspnam (3) +and related functions. +.PP +The GNU C Library ignores databases with unknown names. +Some applications use this to implement special handling for their own +databases. +For example, +.BR sudo (8) +consults the +.B sudoers +database. +Delegation of subordinate user/group IDs +can be configured using the +.B subid +database. +Refer to +.BR subuid (5) +and +.BR subgid (5) +for more details. +.PP +Here is an example +.I /etc/nsswitch.conf +file: +.PP +.in +4n +.EX +passwd: compat +group: compat +shadow: compat +\& +hosts: dns [!UNAVAIL=return] files +networks: nis [NOTFOUND=return] files +ethers: nis [NOTFOUND=return] files +protocols: nis [NOTFOUND=return] files +rpc: nis [NOTFOUND=return] files +services: nis [NOTFOUND=return] files +.EE +.in +.PP +The first column is the database name. +The remaining columns specify: +.IP \[bu] 3 +One or more service specifications, for example, "files", "db", or "nis". +The order of the services on the line determines the order in which +those services will be queried, in turn, until a result is found. +.IP \[bu] +Optional actions to perform if a particular result is obtained +from the preceding service, for example, "[NOTFOUND=return]". +.PP +The service specifications supported on your system depend on the +presence of shared libraries, and are therefore extensible. +Libraries called +.IB /lib/libnss_SERVICE.so. X +will provide the named +.IR SERVICE . +On a standard installation, you can use +"files", "db", "nis", and "nisplus". +For the +.B hosts +database, you can additionally specify "dns". +For the +.BR passwd , +.BR group , +and +.B shadow +databases, you can additionally specify +"compat" (see +.B "Compatibility mode" +below). +The version number +.B X +may be 1 for glibc 2.0, or 2 for glibc 2.1 and later. +On systems with additional libraries installed, you may have access to +further services such as "hesiod", "ldap", "winbind", and "wins". +.PP +An action may also be specified following a service specification. +The action modifies the behavior following a result obtained +from the preceding data source. +Action items take the general form: +.PP +.RS 4 +.RI [ STATUS = ACTION ] +.br +.RI [! STATUS = ACTION ] +.RE +.PP +where +.PP +.RS 4 +.I STATUS +=> +.B success +| +.B notfound +| +.B unavail +| +.B tryagain +.br +.I ACTION +=> +.B return +| +.B continue +| +.B merge +.RE +.PP +The ! negates the test, matching all possible results except the +one specified. +The case of the keywords is not significant. +.PP +The +.I STATUS +value is matched against the result of the lookup function called by +the preceding service specification, and can be one of: +.RS 4 +.TP 12 +.B success +No error occurred and the requested entry is returned. +The default action for this condition is "return". +.TP +.B notfound +The lookup succeeded, but the requested entry was not found. +The default action for this condition is "continue". +.TP +.B unavail +The service is permanently unavailable. +This can mean either that the +required file cannot be read, or, for network services, that the server +is not available or does not allow queries. +The default action for this condition is "continue". +.TP +.B tryagain +The service is temporarily unavailable. +This could mean a file is +locked or a server currently cannot accept more connections. +The default action for this condition is "continue". +.RE +.PP +The +.I ACTION +value can be one of: +.RS 4 +.TP 12 +.B return +Return a result now. +Do not call any further lookup functions. +However, for compatibility reasons, if this is the selected action for the +.B group +database and the +.B notfound +status, and the configuration file does not contain the +.B initgroups +line, the next lookup function is always called, +without affecting the search result. +.TP +.B continue +Call the next lookup function. +.TP +.B merge +.I [SUCCESS=merge] +is used between two database entries. +When a group is located in the first of the two group entries, +processing will continue on to the next one. +If the group is also found in the next entry (and the group name and GID +are an exact match), the member list of the second entry will be added +to the group object to be returned. +Available since glibc 2.24. +Note that merging will not be done for +.BR getgrent (3) +nor will duplicate members be pruned when they occur in both entries +being merged. +.RE +.SS Compatibility mode (compat) +The NSS "compat" service is similar to "files" except that it +additionally permits special entries in corresponding files +for granting users or members of netgroups access to the system. +The following entries are valid in this mode: +.RS 4 +.PP +For +.B passwd +and +.B shadow +databases: +.RS 4 +.TP 12 +.BI + user +Include the specified +.I user +from the NIS passwd/shadow map. +.TP +.BI +@ netgroup +Include all users in the given +.IR netgroup . +.TP +.BI \- user +Exclude the specified +.I user +from the NIS passwd/shadow map. +.TP +.BI \-@ netgroup +Exclude all users in the given +.IR netgroup . +.TP +.B + +Include every user, except previously excluded ones, from the +NIS passwd/shadow map. +.RE +.PP +For +.B group +database: +.RS 4 +.TP 12 +.BI + group +Include the specified +.I group +from the NIS group map. +.TP +.BI \- group +Exclude the specified +.I group +from the NIS group map. +.TP +.B + +Include every group, except previously excluded ones, from the +NIS group map. +.RE +.RE +.PP +By default, the source is "nis", but this may be +overridden by specifying any NSS service except "compat" itself +as the source for the pseudo-databases +.BR passwd_compat , +.BR group_compat , +and +.BR shadow_compat . +.SH FILES +A service named +.I SERVICE +is implemented by a shared object library named +.IB libnss_SERVICE.so. X +that resides in +.IR /lib . +.RS 4 +.TP 25 +.PD 0 +.I /etc/nsswitch.conf +NSS configuration file. +.TP +.IB /lib/libnss_compat.so. X +implements "compat" source. +.TP +.IB /lib/libnss_db.so. X +implements "db" source. +.TP +.IB /lib/libnss_dns.so. X +implements "dns" source. +.TP +.IB /lib/libnss_files.so. X +implements "files" source. +.TP +.IB /lib/libnss_hesiod.so. X +implements "hesiod" source. +.TP +.IB /lib/libnss_nis.so. X +implements "nis" source. +.TP +.IB /lib/libnss_nisplus.so. X +implements "nisplus" source. +.PD +.RE +.PP +The following files are read when "files" source is specified +for respective databases: +.RS 4 +.TP 12 +.PD 0 +.B aliases +.I /etc/aliases +.TP +.B ethers +.I /etc/ethers +.TP +.B group +.I /etc/group +.TP +.B hosts +.I /etc/hosts +.TP +.B initgroups +.I /etc/group +.TP +.B netgroup +.I /etc/netgroup +.TP +.B networks +.I /etc/networks +.TP +.B passwd +.I /etc/passwd +.TP +.B protocols +.I /etc/protocols +.TP +.B publickey +.I /etc/publickey +.TP +.B rpc +.I /etc/rpc +.TP +.B services +.I /etc/services +.TP +.B shadow +.I /etc/shadow +.PD +.RE +.SH NOTES +Starting with glibc 2.33, +.\" https://sourceware.org/bugzilla/show_bug.cgi?id=12459 +.B nsswitch.conf +is automatically reloaded if the file is changed. +In earlier versions, the entire file was read only once within each process. +If the file was later changed, +the process would continue using the old configuration. +.PP +Traditionally, there was only a single source for service information, +often in the form of a single configuration +file (e.g., \fI/etc/passwd\fP). +However, as other name services, such as the Network Information +Service (NIS) and the Domain Name Service (DNS), became popular, +a method was needed +that would be more flexible than fixed search orders coded into +the C library. +The Name Service Switch mechanism, +which was based on the mechanism used by +Sun Microsystems in the Solaris 2 C library, +introduced a cleaner solution to the problem. +.SH SEE ALSO +.BR getent (1), +.BR nss (5) diff --git a/man5/passwd.5 b/man5/passwd.5 new file mode 100644 index 0000000..9b9a136 --- /dev/null +++ b/man5/passwd.5 @@ -0,0 +1,160 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sun Jul 25 10:46:28 1993 by Rik Faith (faith@cs.unc.edu) +.\" Modified Sun Aug 21 18:12:27 1994 by Rik Faith (faith@cs.unc.edu) +.\" Modified Sun Jun 18 01:53:57 1995 by Andries Brouwer (aeb@cwi.nl) +.\" Modified Mon Jan 5 20:24:40 MET 1998 by Michael Haardt +.\" (michael@cantor.informatik.rwth-aachen.de) +.TH passwd 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +passwd \- password file +.SH DESCRIPTION +The +.I /etc/passwd +file is a text file that describes user login accounts for the system. +It should have read permission allowed for all users (many utilities, like +.BR ls (1) +use it to map user IDs to usernames), but write access only for the +superuser. +.PP +In the good old days there was no great problem with this general +read permission. +Everybody could read the encrypted passwords, but the +hardware was too slow to crack a well-chosen password, and moreover the +basic assumption used to be that of a friendly user-community. +These days many people run some version of the shadow password suite, where +.I /etc/passwd +has an \[aq]x\[aq] character in the password field, +and the encrypted passwords are in +.IR /etc/shadow , +which is readable by the superuser only. +.PP +If the encrypted password, whether in +.I /etc/passwd +or in +.IR /etc/shadow , +is an empty string, login is allowed without even asking for a password. +Note that this functionality may be intentionally disabled in applications, +or configurable (for example using the +.RB \[dq] nullok \[dq] +or +.RB \[dq] nonull \[dq] +arguments to +.BR pam_unix (8)). +.PP +If the encrypted password in +.I /etc/passwd +is "\fI*NP*\fP" (without the quotes), +the shadow record should be obtained from an NIS+ server. +.PP +Regardless of whether shadow passwords are used, many system administrators +use an asterisk (*) in the encrypted password field to make sure +that this user can not authenticate themself using a +password. +(But see NOTES below.) +.PP +If you create a new login, first put an asterisk (*) in the password field, +then use +.BR passwd (1) +to set it. +.PP +Each line of the file describes a single user, +and contains seven colon-separated fields: +.PP +.in +4n +.EX +name:password:UID:GID:GECOS:directory:shell +.EE +.in +.PP +The field are as follows: +.TP 12 +.I name +This is the user's login name. +It should not contain capital letters. +.TP +.I password +This is either the encrypted user password, +an asterisk (*), or the letter \[aq]x\[aq]. +(See +.BR pwconv (8) +for an explanation of \[aq]x\[aq].) +.TP +.I UID +The privileged +.I root +login account (superuser) has the user ID 0. +.TP +.I GID +This is the numeric primary group ID for this user. +(Additional groups for the user are defined in the system group file; see +.BR group (5)). +.TP +.I GECOS +This field (sometimes called the "comment field") +is optional and used only for informational purposes. +Usually, it contains the full username. +Some programs (for example, +.BR finger (1)) +display information from this field. +.IP +GECOS stands for "General Electric Comprehensive Operating System", +which was renamed to GCOS when +GE's large systems division was sold to Honeywell. +Dennis Ritchie has reported: "Sometimes we sent printer output or +batch jobs to the GCOS machine. +The gcos field in the password file was a place to stash the +information for the $IDENTcard. +Not elegant." +.TP +.I directory +This is the user's home directory: +the initial directory where the user is placed after logging in. +The value in this field is used to set the +.B HOME +environment variable. +.TP +.I shell +This is the program to run at login (if empty, use +.IR /bin/sh ). +If set to a nonexistent executable, the user will be unable to login +through +.BR login (1). +The value in this field is used to set the +.B SHELL +environment variable. +.SH FILES +.I /etc/passwd +.SH NOTES +If you want to create user groups, there must be an entry in +.IR /etc/group , +or no group will exist. +.PP +If the encrypted password is set to an asterisk (*), the user will be unable +to login using +.BR login (1), +but may still login using +.BR rlogin (1), +run existing processes and initiate new ones through +.BR rsh (1), +.BR cron (8), +.BR at (1), +or mail filters, etc. +Trying to lock an account by simply changing the +shell field yields the same result and additionally allows the use of +.BR su (1). +.SH SEE ALSO +.BR chfn (1), +.BR chsh (1), +.BR login (1), +.BR passwd (1), +.BR su (1), +.BR crypt (3), +.BR getpwent (3), +.BR getpwnam (3), +.BR group (5), +.BR shadow (5), +.BR vipw (8) diff --git a/man5/proc.5 b/man5/proc.5 new file mode 100644 index 0000000..9a48841 --- /dev/null +++ b/man5/proc.5 @@ -0,0 +1,6965 @@ +'\" t +.\" Copyright (C) 1994, 1995 by Daniel Quinlan (quinlan@yggdrasil.com) +.\" and Copyright (C) 2002-2008,2017 Michael Kerrisk <mtk.manpages@gmail.com> +.\" with networking additions from Alan Cox (A.Cox@swansea.ac.uk) +.\" and scsi additions from Michael Neuffer (neuffer@mail.uni-mainz.de) +.\" and sysctl additions from Andries Brouwer (aeb@cwi.nl) +.\" and System V IPC (as well as various other) additions from +.\" Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified 1995-05-17 by faith@cs.unc.edu +.\" Minor changes by aeb and Marty Leisner (leisner@sdsp.mc.xerox.com). +.\" Modified 1996-04-13, 1996-07-22 by aeb@cwi.nl +.\" Modified 2001-12-16 by rwhron@earthlink.net +.\" Modified 2002-07-13 by jbelton@shaw.ca +.\" Modified 2002-07-22, 2003-05-27, 2004-04-06, 2004-05-25 +.\" by Michael Kerrisk <mtk.manpages@gmail.com> +.\" 2004-11-17, mtk -- updated notes on /proc/loadavg +.\" 2004-12-01, mtk, rtsig-max and rtsig-nr went away in Linux 2.6.8 +.\" 2004-12-14, mtk, updated 'statm', and fixed error in order of list +.\" 2005-05-12, mtk, updated 'stat' +.\" 2005-07-13, mtk, added /proc/sys/fs/mqueue/* +.\" 2005-09-16, mtk, Added /proc/sys/fs/suid_dumpable +.\" 2005-09-19, mtk, added /proc/zoneinfo +.\" 2005-03-01, mtk, moved /proc/sys/fs/mqueue/* material to mq_overview.7. +.\" 2008-06-05, mtk, Added /proc/[pid]/oom_score, /proc/[pid]/oom_adj, +.\" /proc/[pid]/limits, /proc/[pid]/mountinfo, /proc/[pid]/mountstats, +.\" and /proc/[pid]/fdinfo/*. +.\" 2008-06-19, mtk, Documented /proc/[pid]/status. +.\" 2008-07-15, mtk, added /proc/config.gz +.\" +.\" FIXME cross check against Documentation/filesystems/proc.txt +.\" to see what information could be imported from that file +.\" into this file. +.\" +.TH proc 5 2023-07-08 "Linux man-pages 6.05.01" +.SH NAME +proc \- process information, system information, and sysctl pseudo-filesystem +.SH DESCRIPTION +The +.B proc +filesystem is a pseudo-filesystem which provides an interface to +kernel data structures. +It is commonly mounted at +.IR /proc . +Typically, it is mounted automatically by the system, +but it can also be mounted manually using a command such as: +.PP +.in +4n +.EX +mount \-t proc proc /proc +.EE +.in +.PP +Most of the files in the +.B proc +filesystem are read-only, +but some files are writable, allowing kernel variables to be changed. +.\" +.SS Mount options +The +.B proc +filesystem supports the following mount options: +.TP +.BR hidepid "=\fIn\fP (since Linux 3.3)" +.\" commit 0499680a42141d86417a8fbaa8c8db806bea1201 +This option controls who can access the information in +.IR /proc/ pid +directories. +The argument, +.IR n , +is one of the following values: +.RS +.TP 4 +0 +Everybody may access all +.IR /proc/ pid +directories. +This is the traditional behavior, +and the default if this mount option is not specified. +.TP +1 +Users may not access files and subdirectories inside any +.IR /proc/ pid +directories but their own (the +.IR /proc/ pid +directories themselves remain visible). +Sensitive files such as +.IR /proc/ pid /cmdline +and +.IR /proc/ pid /status +are now protected against other users. +This makes it impossible to learn whether any user is running a +specific program +(so long as the program doesn't otherwise reveal itself by its behavior). +.\" As an additional bonus, since +.\" .IR /proc/[pid]/cmdline +.\" is inaccessible for other users, +.\" poorly written programs passing sensitive information via +.\" program arguments are now protected against local eavesdroppers. +.TP +2 +As for mode 1, but in addition the +.IR /proc/ pid +directories belonging to other users become invisible. +This means that +.IR /proc/ pid +entries can no longer be used to discover the PIDs on the system. +This doesn't hide the fact that a process with a specific PID value exists +(it can be learned by other means, for example, by "kill \-0 $PID"), +but it hides a process's UID and GID, +which could otherwise be learned by employing +.BR stat (2) +on a +.IR /proc/ pid +directory. +This greatly complicates an attacker's task of gathering +information about running processes (e.g., discovering whether +some daemon is running with elevated privileges, +whether another user is running some sensitive program, +whether other users are running any program at all, and so on). +.RE +.TP +.BR gid "=\fIgid\fP (since Linux 3.3)" +.\" commit 0499680a42141d86417a8fbaa8c8db806bea1201 +Specifies the ID of a group whose members are authorized to +learn process information otherwise prohibited by +.B hidepid +(i.e., users in this group behave as though +.I /proc +was mounted with +.IR hidepid=0 ). +This group should be used instead of approaches such as putting +nonroot users into the +.BR sudoers (5) +file. +.\" +.SS Overview +Underneath +.IR /proc , +there are the following general groups of files and subdirectories: +.TP +.IR /proc/ "pid subdirectories" +Each one of these subdirectories contains files and subdirectories +exposing information about the process with the corresponding process ID. +.IP +Underneath each of the +.IR /proc/ pid +directories, a +.I task +subdirectory contains subdirectories of the form +.IR task/ tid, +which contain corresponding information about each of the threads +in the process, where +.I tid +is the kernel thread ID of the thread. +.IP +The +.IR /proc/ pid +subdirectories are visible when iterating through +.I /proc +with +.BR getdents (2) +(and thus are visible when one uses +.BR ls (1) +to view the contents of +.IR /proc ). +.TP +.IR /proc/ "tid subdirectories" +Each one of these subdirectories contains files and subdirectories +exposing information about the thread with the corresponding thread ID. +The contents of these directories are the same as the corresponding +.IR /proc/ pid /task/ tid +directories. +.IP +The +.IR /proc/ tid +subdirectories are +.I not +visible when iterating through +.I /proc +with +.BR getdents (2) +(and thus are +.I not +visible when one uses +.BR ls (1) +to view the contents of +.IR /proc ). +.TP +.I /proc/self +When a process accesses this magic symbolic link, +it resolves to the process's own +.IR /proc/ pid +directory. +.TP +.I /proc/thread\-self +When a thread accesses this magic symbolic link, +it resolves to the process's own +.IR /proc/self/task/ tid +directory. +.TP +.I /proc/[a\-z]* +Various other files and subdirectories under +.I /proc +expose system-wide information. +.PP +All of the above are described in more detail below. +.\" +.SS Files and directories +The following list provides details of many of the files and directories +under the +.I /proc +hierarchy. +.TP +.IR /proc/ pid +There is a numerical subdirectory for each running process; the +subdirectory is named by the process ID. +Each +.IR /proc/ pid +subdirectory contains the pseudo-files and directories described below. +.IP +The files inside each +.IR /proc/ pid +directory are normally owned by the effective user and +effective group ID of the process. +However, as a security measure, the ownership is made +.I root:root +if the process's "dumpable" attribute is set to a value other than 1. +.IP +Before Linux 4.11, +.\" commit 68eb94f16227336a5773b83ecfa8290f1d6b78ce +.I root:root +meant the "global" root user ID and group ID +(i.e., UID 0 and GID 0 in the initial user namespace). +Since Linux 4.11, +if the process is in a noninitial user namespace that has a +valid mapping for user (group) ID 0 inside the namespace, then +the user (group) ownership of the files under +.IR /proc/ pid +is instead made the same as the root user (group) ID of the namespace. +This means that inside a container, +things work as expected for the container "root" user. +.IP +The process's "dumpable" attribute may change for the following reasons: +.RS +.IP \[bu] 3 +The attribute was explicitly set via the +.BR prctl (2) +.B PR_SET_DUMPABLE +operation. +.IP \[bu] +The attribute was reset to the value in the file +.I /proc/sys/fs/suid_dumpable +(described below), for the reasons described in +.BR prctl (2). +.RE +.IP +Resetting the "dumpable" attribute to 1 reverts the ownership of the +.IR /proc/ pid /* +files to the process's effective UID and GID. +Note, however, that if the effective UID or GID is subsequently modified, +then the "dumpable" attribute may be reset, as described in +.BR prctl (2). +Therefore, it may be desirable to reset the "dumpable" attribute +.I after +making any desired changes to the process's effective UID or GID. +.TP +.IR /proc/ pid /attr +.\" https://lwn.net/Articles/28222/ +.\" From: Stephen Smalley <sds@epoch.ncsc.mil> +.\" To: LKML and others +.\" Subject: [RFC][PATCH] Process Attribute API for Security Modules +.\" Date: 08 Apr 2003 16:17:52 -0400 +.\" +.\" http://www.nsa.gov/research/_files/selinux/papers/module/x362.shtml +.\" +The files in this directory provide an API for security modules. +The contents of this directory are files that can be read and written +in order to set security-related attributes. +This directory was added to support SELinux, +but the intention was that the API be general enough to support +other security modules. +For the purpose of explanation, +examples of how SELinux uses these files are provided below. +.IP +This directory is present only if the kernel was configured with +.BR CONFIG_SECURITY . +.TP +.IR /proc/ pid /attr/current " (since Linux 2.6.0)" +The contents of this file represent the current +security attributes of the process. +.IP +In SELinux, this file is used to get the security context of a process. +Prior to Linux 2.6.11, this file could not be used to set the security +context (a write was always denied), since SELinux limited process security +transitions to +.BR execve (2) +(see the description of +.IR /proc/ pid /attr/exec , +below). +Since Linux 2.6.11, SELinux lifted this restriction and began supporting +"set" operations via writes to this node if authorized by policy, +although use of this operation is only suitable for applications that are +trusted to maintain any desired separation between the old and new security +contexts. +.IP +Prior to Linux 2.6.28, SELinux did not allow threads within a +multithreaded process to set their security context via this node +as it would yield an inconsistency among the security contexts of the +threads sharing the same memory space. +Since Linux 2.6.28, SELinux lifted +this restriction and began supporting "set" operations for threads within +a multithreaded process if the new security context is bounded by the old +security context, where the bounded relation is defined in policy and +guarantees that the new security context has a subset of the permissions +of the old security context. +.IP +Other security modules may choose to support "set" operations via +writes to this node. +.TP +.IR /proc/ pid /attr/exec " (since Linux 2.6.0)" +This file represents the attributes to assign to the +process upon a subsequent +.BR execve (2). +.IP +In SELinux, +this is needed to support role/domain transitions, and +.BR execve (2) +is the preferred point to make such transitions because it offers better +control over the initialization of the process in the new security label +and the inheritance of state. +In SELinux, this attribute is reset on +.BR execve (2) +so that the new program reverts to the default behavior for any +.BR execve (2) +calls that it may make. +In SELinux, a process can set +only its own +.IR /proc/ pid /attr/exec +attribute. +.TP +.IR /proc/ pid /attr/fscreate " (since Linux 2.6.0)" +This file represents the attributes to assign to files +created by subsequent calls to +.BR open (2), +.BR mkdir (2), +.BR symlink (2), +and +.BR mknod (2) +.IP +SELinux employs this file to support creation of a file +(using the aforementioned system calls) +in a secure state, +so that there is no risk of inappropriate access being obtained +between the time of creation and the time that attributes are set. +In SELinux, this attribute is reset on +.BR execve (2), +so that the new program reverts to the default behavior for +any file creation calls it may make, but the attribute will persist +across multiple file creation calls within a program unless it is +explicitly reset. +In SELinux, a process can set only its own +.IR /proc/ pid /attr/fscreate +attribute. +.TP +.IR /proc/ pid /attr/keycreate " (since Linux 2.6.18)" +.\" commit 4eb582cf1fbd7b9e5f466e3718a59c957e75254e +If a process writes a security context into this file, +all subsequently created keys +.RB ( add_key (2)) +will be labeled with this context. +For further information, see the kernel source file +.I Documentation/security/keys/core.rst +(or file +.\" commit b68101a1e8f0263dbc7b8375d2a7c57c6216fb76 +.I Documentation/security/keys.txt +between Linux 3.0 and Linux 4.13, or +.\" commit d410fa4ef99112386de5f218dd7df7b4fca910b4 +.I Documentation/keys.txt +before Linux 3.0). +.TP +.IR /proc/ pid /attr/prev " (since Linux 2.6.0)" +This file contains the security context of the process before the last +.BR execve (2); +that is, the previous value of +.IR /proc/ pid /attr/current . +.TP +.IR /proc/ pid /attr/socketcreate " (since Linux 2.6.18)" +.\" commit 42c3e03ef6b298813557cdb997bd6db619cd65a2 +If a process writes a security context into this file, +all subsequently created sockets will be labeled with this context. +.TP +.IR /proc/ pid /autogroup " (since Linux 2.6.38)" +.\" commit 5091faa449ee0b7d73bc296a93bca9540fc51d0a +See +.BR sched (7). +.TP +.IR /proc/ pid /auxv " (since Linux 2.6.0)" +.\" Precisely: Linux 2.6.0-test7 +This contains the contents of the ELF interpreter information passed +to the process at exec time. +The format is one \fIunsigned long\fP ID +plus one \fIunsigned long\fP value for each entry. +The last entry contains two zeros. +See also +.BR getauxval (3). +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /cgroup " (since Linux 2.6.24)" +See +.BR cgroups (7). +.TP +.IR /proc/ pid /clear_refs " (since Linux 2.6.22)" +.\" commit b813e931b4c8235bb42e301096ea97dbdee3e8fe (2.6.22) +.\" commit 398499d5f3613c47f2143b8c54a04efb5d7a6da9 (2.6.32) +.\" commit 040fa02077de01c7e08fa75be6125e4ca5636011 (3.11) +.\" +.\" "Clears page referenced bits shown in smaps output" +.\" write-only, writable only by the owner of the process +.IP +This is a write-only file, writable only by owner of the process. +.IP +The following values may be written to the file: +.RS +.TP +1 (since Linux 2.6.22) +.\" Internally: CLEAR_REFS_ALL +Reset the PG_Referenced and ACCESSED/YOUNG +bits for all the pages associated with the process. +(Before Linux 2.6.32, writing any nonzero value to this file +had this effect.) +.TP +2 (since Linux 2.6.32) +.\" Internally: CLEAR_REFS_ANON +Reset the PG_Referenced and ACCESSED/YOUNG +bits for all anonymous pages associated with the process. +.TP +3 (since Linux 2.6.32) +.\" Internally: CLEAR_REFS_MAPPED +Reset the PG_Referenced and ACCESSED/YOUNG +bits for all file-mapped pages associated with the process. +.RE +.IP +Clearing the PG_Referenced and ACCESSED/YOUNG bits provides a method +to measure approximately how much memory a process is using. +One first inspects the values in the "Referenced" fields +for the VMAs shown in +.IR /proc/ pid /smaps +to get an idea of the memory footprint of the +process. +One then clears the PG_Referenced and ACCESSED/YOUNG bits +and, after some measured time interval, +once again inspects the values in the "Referenced" fields +to get an idea of the change in memory footprint of the +process during the measured interval. +If one is interested only in inspecting the selected mapping types, +then the value 2 or 3 can be used instead of 1. +.IP +Further values can be written to affect different properties: +.RS +.TP +4 (since Linux 3.11) +Clear the soft-dirty bit for all the pages associated with the process. +.\" Internally: CLEAR_REFS_SOFT_DIRTY +This is used (in conjunction with +.IR /proc/ pid /pagemap ) +by the check-point restore system to discover which pages of a process +have been dirtied since the file +.IR /proc/ pid /clear_refs +was written to. +.TP +5 (since Linux 4.0) +.\" Internally: CLEAR_REFS_MM_HIWATER_RSS +Reset the peak resident set size ("high water mark") to the process's +current resident set size value. +.RE +.IP +Writing any value to +.IR /proc/ pid /clear_refs +other than those listed above has no effect. +.IP +The +.IR /proc/ pid /clear_refs +file is present only if the +.B CONFIG_PROC_PAGE_MONITOR +kernel configuration option is enabled. +.TP +.IR /proc/ pid /cmdline +This read-only file holds the complete command line for the process, +unless the process is a zombie. +.\" In Linux 2.3.26, this also used to be true if the process was swapped out. +In the latter case, there is nothing in this file: +that is, a read on this file will return 0 characters. +.IP +For processes which are still running, +the command-line arguments appear in this file +in the same layout as they do in process memory: +If the process is well-behaved, +it is a set of strings separated by null bytes (\[aq]\e0\[aq]), +with a further null byte after the last string. +.IP +This is the common case, +but processes have the freedom to +override the memory region and +break assumptions about the contents or format of the +.IR /proc/ pid /cmdline +file. +.IP +If, after an +.BR execve (2), +the process modifies its +.I argv +strings, those changes will show up here. +This is not the same thing as modifying the +.I argv +array. +.IP +Furthermore, a process may change the memory location that this file refers via +.BR prctl (2) +operations such as +.BR PR_SET_MM_ARG_START . +.IP +Think of this file as the command line that the process wants you to see. +.TP +.IR /proc/ pid /comm " (since Linux 2.6.33)" +.\" commit 4614a696bd1c3a9af3a08f0e5874830a85b889d4 +This file exposes the process's +.I comm +value\[em]that is, the command name associated with the process. +Different threads in the same process may have different +.I comm +values, accessible via +.IR /proc/ pid /task/ tid /comm . +A thread may modify its +.I comm +value, or that of any of other thread in the same thread group (see +the discussion of +.B CLONE_THREAD +in +.BR clone (2)), +by writing to the file +.IR /proc/self/task/ tid /comm . +Strings longer than +.B TASK_COMM_LEN +(16) characters (including the terminating null byte) are silently truncated. +.IP +This file provides a superset of the +.BR prctl (2) +.B PR_SET_NAME +and +.B PR_GET_NAME +operations, and is employed by +.BR pthread_setname_np (3) +when used to rename threads other than the caller. +The value in this file is used for the +.I %e +specifier in +.IR /proc/sys/kernel/core_pattern ; +see +.BR core (5). +.TP +.IR /proc/ pid /coredump_filter " (since Linux 2.6.23)" +See +.BR core (5). +.TP +.IR /proc/ pid /cpuset " (since Linux 2.6.12)" +.\" and/proc/[pid]/task/[tid]/cpuset +See +.BR cpuset (7). +.TP +.IR /proc/ pid /cwd +This is a symbolic link to the current working directory of the process. +To find out the current working directory of process 20, +for instance, you can do this: +.IP +.in +4n +.EX +.RB "$" " cd /proc/20/cwd; pwd \-P" +.EE +.in +.IP +.\" The following was still true as at kernel 2.6.13 +In a multithreaded process, the contents of this symbolic link +are not available if the main thread has already terminated +(typically by calling +.BR pthread_exit (3)). +.IP +Permission to dereference or read +.RB ( readlink (2)) +this symbolic link is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /environ +This file contains the initial environment that was set +when the currently executing program was started via +.BR execve (2). +The entries are separated by null bytes (\[aq]\e0\[aq]), +and there may be a null byte at the end. +Thus, to print out the environment of process 1, you would do: +.IP +.in +4n +.EX +.RB "$" " cat /proc/1/environ | tr \[aq]\e000\[aq] \[aq]\en\[aq]" +.EE +.in +.IP +If, after an +.BR execve (2), +the process modifies its environment +(e.g., by calling functions such as +.BR putenv (3) +or modifying the +.BR environ (7) +variable directly), +this file will +.I not +reflect those changes. +.IP +Furthermore, a process may change the memory location that this file refers via +.BR prctl (2) +operations such as +.BR PR_SET_MM_ENV_START . +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /exe +Under Linux 2.2 and later, this file is a symbolic link +containing the actual pathname of the executed command. +This symbolic link can be dereferenced normally; attempting to open +it will open the executable. +You can even type +.IR /proc/ pid /exe +to run another copy of the same executable that is being run by +process +.IR pid . +If the pathname has been unlinked, the symbolic link will contain the +string \[aq]\ (deleted)\[aq] appended to the original pathname. +.\" The following was still true as at kernel 2.6.13 +In a multithreaded process, the contents of this symbolic link +are not available if the main thread has already terminated +(typically by calling +.BR pthread_exit (3)). +.IP +Permission to dereference or read +.RB ( readlink (2)) +this symbolic link is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.IP +Under Linux 2.0 and earlier, +.IR /proc/ pid /exe +is a pointer to the binary which was executed, +and appears as a symbolic link. +A +.BR readlink (2) +call on this file under Linux 2.0 returns a string in the format: +.IP +.in +4n +.EX +[device]:inode +.EE +.in +.IP +For example, [0301]:1502 would be inode 1502 on device major 03 (IDE, +MFM, etc. drives) minor 01 (first partition on the first drive). +.IP +.BR find (1) +with the +.I \-inum +option can be used to locate the file. +.TP +.IR /proc/ pid /fd/ +This is a subdirectory containing one entry for each file which the +process has open, named by its file descriptor, and which is a +symbolic link to the actual file. +Thus, 0 is standard input, 1 standard output, 2 standard error, and so on. +.IP +For file descriptors for pipes and sockets, +the entries will be symbolic links whose content is the +file type with the inode. +A +.BR readlink (2) +call on this file returns a string in the format: +.IP +.in +4n +.EX +type:[inode] +.EE +.in +.IP +For example, +.I socket:[2248868] +will be a socket and its inode is 2248868. +For sockets, that inode can be used to find more information +in one of the files under +.IR /proc/net/ . +.IP +For file descriptors that have no corresponding inode +(e.g., file descriptors produced by +.BR bpf (2), +.BR epoll_create (2), +.BR eventfd (2), +.BR inotify_init (2), +.BR perf_event_open (2), +.BR signalfd (2), +.BR timerfd_create (2), +and +.BR userfaultfd (2)), +the entry will be a symbolic link with contents of the form +.IP +.in +4n +.EX +.RI anon_inode: file-type +.EE +.in +.IP +In many cases (but not all), the +.I file-type +is surrounded by square brackets. +.IP +For example, an epoll file descriptor will have a symbolic link +whose content is the string +.IR "anon_inode:[eventpoll]" . +.IP +.\"The following was still true as at kernel 2.6.13 +In a multithreaded process, the contents of this directory +are not available if the main thread has already terminated +(typically by calling +.BR pthread_exit (3)). +.IP +Programs that take a filename as a command-line argument, +but don't take input from standard input if no argument is supplied, +and programs that write to a file named as a command-line argument, +but don't send their output to standard output +if no argument is supplied, can nevertheless be made to use +standard input or standard output by using +.IR /proc/ pid /fd +files as command-line arguments. +For example, assuming that +.I \-i +is the flag designating an input file and +.I \-o +is the flag designating an output file: +.IP +.in +4n +.EX +.RB "$" " foobar \-i /proc/self/fd/0 \-o /proc/self/fd/1 ..." +.EE +.in +.IP +and you have a working filter. +.\" The following is not true in my tests (MTK): +.\" Note that this will not work for +.\" programs that seek on their files, as the files in the fd directory +.\" are not seekable. +.IP +.I /proc/self/fd/N +is approximately the same as +.I /dev/fd/N +in some UNIX and UNIX-like systems. +Most Linux MAKEDEV scripts symbolically link +.I /dev/fd +to +.IR /proc/self/fd , +in fact. +.IP +Most systems provide symbolic links +.IR /dev/stdin , +.IR /dev/stdout , +and +.IR /dev/stderr , +which respectively link to the files +.IR 0 , +.IR 1 , +and +.I 2 +in +.IR /proc/self/fd . +Thus the example command above could be written as: +.IP +.in +4n +.EX +.RB "$" " foobar \-i /dev/stdin \-o /dev/stdout ..." +.EE +.in +.IP +Permission to dereference or read +.RB ( readlink (2)) +the symbolic links in this directory is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.IP +Note that for file descriptors referring to inodes +(pipes and sockets, see above), +those inodes still have permission bits and ownership information +distinct from those of the +.IR /proc/ pid /fd +entry, +and that the owner may differ from the user and group IDs of the process. +An unprivileged process may lack permissions to open them, as in this example: +.IP +.in +4n +.EX +.RB "$" " echo test | sudo \-u nobody cat" +test +.RB "$" " echo test | sudo \-u nobody cat /proc/self/fd/0" +cat: /proc/self/fd/0: Permission denied +.EE +.in +.IP +File descriptor 0 refers to the pipe created by the shell +and owned by that shell's user, which is not +.IR nobody , +so +.B cat +does not have permission +to create a new file descriptor to read from that inode, +even though it can still read from its existing file descriptor 0. +.TP +.IR /proc/ pid /fdinfo/ " (since Linux 2.6.22)" +This is a subdirectory containing one entry for each file which the +process has open, named by its file descriptor. +The files in this directory are readable only by the owner of the process. +The contents of each file can be read to obtain information +about the corresponding file descriptor. +The content depends on the type of file referred to by the +corresponding file descriptor. +.IP +For regular files and directories, we see something like: +.IP +.in +4n +.EX +.RB "$" " cat /proc/12015/fdinfo/4" +pos: 1000 +flags: 01002002 +mnt_id: 21 +.EE +.in +.IP +The fields are as follows: +.RS +.TP +.I pos +This is a decimal number showing the file offset. +.TP +.I flags +This is an octal number that displays the +file access mode and file status flags (see +.BR open (2)). +If the close-on-exec file descriptor flag is set, then +.I flags +will also include the value +.BR O_CLOEXEC . +.IP +Before Linux 3.1, +.\" commit 1117f72ea0217ba0cc19f05adbbd8b9a397f5ab7 +this field incorrectly displayed the setting of +.B O_CLOEXEC +at the time the file was opened, +rather than the current setting of the close-on-exec flag. +.TP +.I +.I mnt_id +This field, present since Linux 3.15, +.\" commit 49d063cb353265c3af701bab215ac438ca7df36d +is the ID of the mount containing this file. +See the description of +.IR /proc/ pid /mountinfo . +.RE +.IP +For eventfd file descriptors (see +.BR eventfd (2)), +we see (since Linux 3.8) +.\" commit cbac5542d48127b546a23d816380a7926eee1c25 +the following fields: +.IP +.in +4n +.EX +pos: 0 +flags: 02 +mnt_id: 10 +eventfd\-count: 40 +.EE +.in +.IP +.I eventfd\-count +is the current value of the eventfd counter, in hexadecimal. +.IP +For epoll file descriptors (see +.BR epoll (7)), +we see (since Linux 3.8) +.\" commit 138d22b58696c506799f8de759804083ff9effae +the following fields: +.IP +.in +4n +.EX +pos: 0 +flags: 02 +mnt_id: 10 +tfd: 9 events: 19 data: 74253d2500000009 +tfd: 7 events: 19 data: 74253d2500000007 +.EE +.in +.IP +Each of the lines beginning +.I tfd +describes one of the file descriptors being monitored via +the epoll file descriptor (see +.BR epoll_ctl (2) +for some details). +The +.I tfd +field is the number of the file descriptor. +The +.I events +field is a hexadecimal mask of the events being monitored for this file +descriptor. +The +.I data +field is the data value associated with this file descriptor. +.IP +For signalfd file descriptors (see +.BR signalfd (2)), +we see (since Linux 3.8) +.\" commit 138d22b58696c506799f8de759804083ff9effae +the following fields: +.IP +.in +4n +.EX +pos: 0 +flags: 02 +mnt_id: 10 +sigmask: 0000000000000006 +.EE +.in +.IP +.I sigmask +is the hexadecimal mask of signals that are accepted via this +signalfd file descriptor. +(In this example, bits 2 and 3 are set, corresponding to the signals +.B SIGINT +and +.BR SIGQUIT ; +see +.BR signal (7).) +.IP +For inotify file descriptors (see +.BR inotify (7)), +we see (since Linux 3.8) +the following fields: +.IP +.in +4n +.EX +pos: 0 +flags: 00 +mnt_id: 11 +inotify wd:2 ino:7ef82a sdev:800001 mask:800afff ignored_mask:0 fhandle\-bytes:8 fhandle\-type:1 f_handle:2af87e00220ffd73 +inotify wd:1 ino:192627 sdev:800001 mask:800afff ignored_mask:0 fhandle\-bytes:8 fhandle\-type:1 f_handle:27261900802dfd73 +.EE +.in +.IP +Each of the lines beginning with "inotify" displays information about +one file or directory that is being monitored. +The fields in this line are as follows: +.RS +.TP +.I wd +A watch descriptor number (in decimal). +.TP +.I ino +The inode number of the target file (in hexadecimal). +.TP +.I sdev +The ID of the device where the target file resides (in hexadecimal). +.TP +.I mask +The mask of events being monitored for the target file (in hexadecimal). +.RE +.IP +If the kernel was built with exportfs support, the path to the target +file is exposed as a file handle, via three hexadecimal fields: +.IR fhandle\-bytes , +.IR fhandle\-type , +and +.IR f_handle . +.IP +For fanotify file descriptors (see +.BR fanotify (7)), +we see (since Linux 3.8) +the following fields: +.IP +.in +4n +.EX +pos: 0 +flags: 02 +mnt_id: 11 +fanotify flags:0 event\-flags:88002 +fanotify ino:19264f sdev:800001 mflags:0 mask:1 ignored_mask:0 fhandle\-bytes:8 fhandle\-type:1 f_handle:4f261900a82dfd73 +.EE +.in +.IP +The fourth line displays information defined when the fanotify group +was created via +.BR fanotify_init (2): +.RS +.TP +.I flags +The +.I flags +argument given to +.BR fanotify_init (2) +(expressed in hexadecimal). +.TP +.I event\-flags +The +.I event_f_flags +argument given to +.BR fanotify_init (2) +(expressed in hexadecimal). +.RE +.IP +Each additional line shown in the file contains information +about one of the marks in the fanotify group. +Most of these fields are as for inotify, except: +.RS +.TP +.I mflags +The flags associated with the mark +(expressed in hexadecimal). +.TP +.I mask +The events mask for this mark +(expressed in hexadecimal). +.TP +.I ignored_mask +The mask of events that are ignored for this mark +(expressed in hexadecimal). +.RE +.IP +For details on these fields, see +.BR fanotify_mark (2). +.IP +For timerfd file descriptors (see +.BR timerfd (2)), +we see (since Linux 3.17) +.\" commit af9c4957cf212ad9cf0bee34c95cb11de5426e85 +the following fields: +.IP +.in +4n +.EX +pos: 0 +flags: 02004002 +mnt_id: 13 +clockid: 0 +ticks: 0 +settime flags: 03 +it_value: (7695568592, 640020877) +it_interval: (0, 0) +.EE +.in +.RS +.TP +.I clockid +This is the numeric value of the clock ID +(corresponding to one of the +.B CLOCK_* +constants defined via +.IR <time.h> ) +that is used to mark the progress of the timer (in this example, 0 is +.BR CLOCK_REALTIME ). +.TP +.I ticks +This is the number of timer expirations that have occurred, +(i.e., the value that +.BR read (2) +on it would return). +.TP +.I settime flags +This field lists the flags with which the timerfd was last armed (see +.BR timerfd_settime (2)), +in octal +(in this example, both +.B TFD_TIMER_ABSTIME +and +.B TFD_TIMER_CANCEL_ON_SET +are set). +.TP +.I it_value +This field contains the amount of time until the timer will next expire, +expressed in seconds and nanoseconds. +This is always expressed as a relative value, +regardless of whether the timer was created using the +.B TFD_TIMER_ABSTIME +flag. +.TP +.I it_interval +This field contains the interval of the timer, +in seconds and nanoseconds. +(The +.I it_value +and +.I it_interval +fields contain the values that +.BR timerfd_gettime (2) +on this file descriptor would return.) +.RE +.TP +.IR /proc/ pid /gid_map " (since Linux 3.5)" +See +.BR user_namespaces (7). +.TP +.IR /proc/ pid /io " (since Linux 2.6.20)" +.\" commit 7c3ab7381e79dfc7db14a67c6f4f3285664e1ec2 +This file contains I/O statistics for the process, for example: +.IP +.in +4n +.EX +.RB "#" " cat /proc/3828/io" +rchar: 323934931 +wchar: 323929600 +syscr: 632687 +syscw: 632675 +read_bytes: 0 +write_bytes: 323932160 +cancelled_write_bytes: 0 +.EE +.in +.IP +The fields are as follows: +.RS +.TP +.IR rchar ": characters read" +The number of bytes which this task has caused to be read from storage. +This is simply the sum of bytes which this process passed to +.BR read (2) +and similar system calls. +It includes things such as terminal I/O and +is unaffected by whether or not actual +physical disk I/O was required (the read might have been satisfied from +pagecache). +.TP +.IR wchar ": characters written" +The number of bytes which this task has caused, or shall cause to be written +to disk. +Similar caveats apply here as with +.IR rchar . +.TP +.IR syscr ": read syscalls" +Attempt to count the number of read I/O operations\[em]that is, +system calls such as +.BR read (2) +and +.BR pread (2). +.TP +.IR syscw ": write syscalls" +Attempt to count the number of write I/O operations\[em]that is, +system calls such as +.BR write (2) +and +.BR pwrite (2). +.TP +.IR read_bytes ": bytes read" +Attempt to count the number of bytes which this process really did cause to +be fetched from the storage layer. +This is accurate for block-backed filesystems. +.TP +.IR write_bytes ": bytes written" +Attempt to count the number of bytes which this process caused to be sent to +the storage layer. +.TP +.IR cancelled_write_bytes : +The big inaccuracy here is truncate. +If a process writes 1 MB to a file and then deletes the file, +it will in fact perform no writeout. +But it will have been accounted as having caused 1 MB of write. +In other words: this field represents the number of bytes which this process +caused to not happen, by truncating pagecache. +A task can cause "negative" I/O too. +If this task truncates some dirty pagecache, +some I/O which another task has been accounted for +(in its +.IR write_bytes ) +will not be happening. +.RE +.IP +.IR Note : +In the current implementation, things are a bit racy on 32-bit systems: +if process A reads process B's +.IR /proc/ pid /io +while process B is updating one of these 64-bit counters, +process A could see an intermediate result. +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /limits " (since Linux 2.6.24)" +This file displays the soft limit, hard limit, and units of measurement +for each of the process's resource limits (see +.BR getrlimit (2)). +Up to and including Linux 2.6.35, +this file is protected to allow reading only by the real UID of the process. +Since Linux 2.6.36, +.\" commit 3036e7b490bf7878c6dae952eec5fb87b1106589 +this file is readable by all users on the system. +.\" FIXME Describe /proc/[pid]/loginuid +.\" Added in Linux 2.6.11; updating requires CAP_AUDIT_CONTROL +.\" CONFIG_AUDITSYSCALL +.TP +.IR /proc/ pid /map_files/ " (since Linux 3.3)" +.\" commit 640708a2cff7f81e246243b0073c66e6ece7e53e +This subdirectory contains entries corresponding to memory-mapped +files (see +.BR mmap (2)). +Entries are named by memory region start and end +address pair (expressed as hexadecimal numbers), +and are symbolic links to the mapped files themselves. +Here is an example, +with the output wrapped and reformatted to fit on an 80-column display: +.IP +.in +4n +.EX +.RB "#" " ls \-l /proc/self/map_files/" +lr\-\-\-\-\-\-\-\-. 1 root root 64 Apr 16 21:31 + 3252e00000\-3252e20000 \-> /usr/lib64/ld\-2.15.so +\&... +.EE +.in +.IP +Although these entries are present for memory regions that were +mapped with the +.B MAP_FILE +flag, the way anonymous shared memory (regions created with the +.B MAP_ANON | MAP_SHARED +flags) +is implemented in Linux +means that such regions also appear on this directory. +Here is an example where the target file is the deleted +.I /dev/zero +one: +.IP +.in +4n +.EX +lrw\-\-\-\-\-\-\-. 1 root root 64 Apr 16 21:33 + 7fc075d2f000\-7fc075e6f000 \-> /dev/zero (deleted) +.EE +.in +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.IP +Until Linux 4.3, +.\" commit bdb4d100afe9818aebd1d98ced575c5ef143456c +this directory appeared only if the +.B CONFIG_CHECKPOINT_RESTORE +kernel configuration option was enabled. +.IP +Capabilities are required to read the contents of the symbolic links in +this directory: before Linux 5.9, the reading process requires +.B CAP_SYS_ADMIN +in the initial user namespace; +since Linux 5.9, the reading process must have either +.B CAP_SYS_ADMIN +or +.B CAP_CHECKPOINT_RESTORE +in the initial (i.e. root) user namespace. +.TP +.IR /proc/ pid /maps +A file containing the currently mapped memory regions and their access +permissions. +See +.BR mmap (2) +for some further information about memory mappings. +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.IP +The format of the file is: +.IP +.in +4n +.EX +.I "address perms offset dev inode pathname" +00400000\-00452000 r\-xp 00000000 08:02 173521 /usr/bin/dbus\-daemon +00651000\-00652000 r\-\-p 00051000 08:02 173521 /usr/bin/dbus\-daemon +00652000\-00655000 rw\-p 00052000 08:02 173521 /usr/bin/dbus\-daemon +00e03000\-00e24000 rw\-p 00000000 00:00 0 [heap] +00e24000\-011f7000 rw\-p 00000000 00:00 0 [heap] +\&... +35b1800000\-35b1820000 r\-xp 00000000 08:02 135522 /usr/lib64/ld\-2.15.so +35b1a1f000\-35b1a20000 r\-\-p 0001f000 08:02 135522 /usr/lib64/ld\-2.15.so +35b1a20000\-35b1a21000 rw\-p 00020000 08:02 135522 /usr/lib64/ld\-2.15.so +35b1a21000\-35b1a22000 rw\-p 00000000 00:00 0 +35b1c00000\-35b1dac000 r\-xp 00000000 08:02 135870 /usr/lib64/libc\-2.15.so +35b1dac000\-35b1fac000 \-\-\-p 001ac000 08:02 135870 /usr/lib64/libc\-2.15.so +35b1fac000\-35b1fb0000 r\-\-p 001ac000 08:02 135870 /usr/lib64/libc\-2.15.so +35b1fb0000\-35b1fb2000 rw\-p 001b0000 08:02 135870 /usr/lib64/libc\-2.15.so +\&... +f2c6ff8c000\-7f2c7078c000 rw\-p 00000000 00:00 0 [stack:986] +\&... +7fffb2c0d000\-7fffb2c2e000 rw\-p 00000000 00:00 0 [stack] +7fffb2d48000\-7fffb2d49000 r\-xp 00000000 00:00 0 [vdso] +.EE +.in +.IP +The +.I address +field is the address space in the process that the mapping occupies. +The +.I perms +field is a set of permissions: +.IP +.in +4n +.EX +r = read +w = write +x = execute +s = shared +p = private (copy on write) +.EE +.in +.IP +The +.I offset +field is the offset into the file/whatever; +.I dev +is the device +(major:minor); +.I inode +is the inode on that device. +0 indicates that no inode is associated with the memory region, +as would be the case with BSS (uninitialized data). +.IP +The +.I pathname +field will usually be the file that is backing the mapping. +For ELF files, +you can easily coordinate with the +.I offset +field by looking at the +Offset field in the ELF program headers +.RI ( "readelf\ \-l" ). +.IP +There are additional helpful pseudo-paths: +.RS +.TP +.I [stack] +The initial process's (also known as the main thread's) stack. +.TP +.IR [stack: tid ] " (from Linux 3.4 to Linux 4.4)" +.\" commit b76437579d1344b612cf1851ae610c636cec7db0 (added) +.\" commit 65376df582174ffcec9e6471bf5b0dd79ba05e4a (removed) +A thread's stack (where the +.I tid +is a thread ID). +It corresponds to the +.IR /proc/ pid /task/ tid / +path. +This field was removed in Linux 4.5, since providing this information +for a process with large numbers of threads is expensive. +.TP +.I [vdso] +The virtual dynamically linked shared object. +See +.BR vdso (7). +.TP +.I [heap] +The process's heap. +.TP +.IR [anon: name ] " (since Linux 5.17)" +.\" Commit 9a10064f5625d5572c3626c1516e0bebc6c9fe9b +A named private anonymous mapping. +Set with +.BR prctl (2) +.BR PR_SET_VMA_ANON_NAME . +.TP +.IR [anon_shmem: name ] " (since Linux 6.2)" +.\" Commit d09e8ca6cb93bb4b97517a18fbbf7eccb0e9ff43 +A named shared anonymous mapping. +Set with +.BR prctl (2) +.BR PR_SET_VMA_ANON_NAME . +.in +.RE +.IP +If the +.I pathname +field is blank, +this is an anonymous mapping as obtained via +.BR mmap (2). +There is no easy way to coordinate this back to a process's source, +short of running it through +.BR gdb (1), +.BR strace (1), +or similar. +.IP +.I pathname +is shown unescaped except for newline characters, which are replaced +with an octal escape sequence. +As a result, it is not possible to determine whether the original +pathname contained a newline character or the literal +.I \e012 +character sequence. +.IP +If the mapping is file-backed and the file has been deleted, the string +" (deleted)" is appended to the pathname. +Note that this is ambiguous too. +.IP +Under Linux 2.0, there is no field giving pathname. +.TP +.IR /proc/ pid /mem +This file can be used to access the pages of a process's memory through +.BR open (2), +.BR read (2), +and +.BR lseek (2). +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_ATTACH_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /mountinfo " (since Linux 2.6.26)" +.\" This info adapted from Documentation/filesystems/proc.txt +.\" commit 2d4d4864ac08caff5c204a752bd004eed4f08760 +This file contains information about mounts +in the process's mount namespace (see +.BR mount_namespaces (7)). +It supplies various information +(e.g., propagation state, root of mount for bind mounts, +identifier for each mount and its parent) that is missing from the (older) +.IR /proc/ pid /mounts +file, and fixes various other problems with that file +(e.g., nonextensibility, +failure to distinguish per-mount versus per-superblock options). +.IP +The file contains lines of the form: +.IP +.EX +36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 \- ext3 /dev/root rw,errors=continue +(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) +.EE +.IP +The numbers in parentheses are labels for the descriptions below: +.RS 7 +.TP 5 +(1) +mount ID: a unique ID for the mount (may be reused after +.BR umount (2)). +.TP +(2) +parent ID: the ID of the parent mount +(or of self for the root of this mount namespace's mount tree). +.IP +If a new mount is stacked on top of a previous existing mount +(so that it hides the existing mount) at pathname P, +then the parent of the new mount is the previous mount at that location. +Thus, when looking at all the mounts stacked at a particular location, +the top-most mount is the one that is not the parent +of any other mount at the same location. +(Note, however, that this top-most mount will be accessible only if +the longest path subprefix of P that is a mount point +is not itself hidden by a stacked mount.) +.IP +If the parent mount lies outside the process's root directory (see +.BR chroot (2)), +the ID shown here won't have a corresponding record in +.I mountinfo +whose mount ID (field 1) matches this parent mount ID +(because mounts that lie outside the process's root directory +are not shown in +.IR mountinfo ). +As a special case of this point, +the process's root mount may have a parent mount +(for the initramfs filesystem) that lies +.\" Miklos Szeredi, Nov 2017: The hidden one is the initramfs, I believe +.\" mtk: In the initial mount namespace, this hidden ID has the value 0 +outside the process's root directory, +and an entry for that mount will not appear in +.IR mountinfo . +.TP +(3) +major:minor: the value of +.I st_dev +for files on this filesystem (see +.BR stat (2)). +.TP +(4) +root: the pathname of the directory in the filesystem +which forms the root of this mount. +.TP +(5) +mount point: the pathname of the mount point relative +to the process's root directory. +.TP +(6) +mount options: per-mount options (see +.BR mount (2)). +.TP +(7) +optional fields: zero or more fields of the form "tag[:value]"; see below. +.TP +(8) +separator: the end of the optional fields is marked by a single hyphen. +.TP +(9) +filesystem type: the filesystem type in the form "type[.subtype]". +.TP +(10) +mount source: filesystem-specific information or "none". +.TP +(11) +super options: per-superblock options (see +.BR mount (2)). +.RE +.IP +Currently, the possible optional fields are +.IR shared , +.IR master , +.IR propagate_from , +and +.IR unbindable . +See +.BR mount_namespaces (7) +for a description of these fields. +Parsers should ignore all unrecognized optional fields. +.IP +For more information on mount propagation see +.I Documentation/filesystems/sharedsubtree.rst +(or +.I Documentation/filesystems/sharedsubtree.txt +before Linux 5.8) +in the Linux kernel source tree. +.TP +.IR /proc/ pid /mounts " (since Linux 2.4.19)" +This file lists all the filesystems currently mounted in the +process's mount namespace (see +.BR mount_namespaces (7)). +The format of this file is documented in +.BR fstab (5). +.IP +Since Linux 2.6.15, this file is pollable: +after opening the file for reading, a change in this file +(i.e., a filesystem mount or unmount) causes +.BR select (2) +to mark the file descriptor as having an exceptional condition, and +.BR poll (2) +and +.BR epoll_wait (2) +mark the file as having a priority event +.RB ( POLLPRI ). +(Before Linux 2.6.30, +a change in this file was indicated by the file descriptor +being marked as readable for +.BR select (2), +and being marked as having an error condition for +.BR poll (2) +and +.BR epoll_wait (2).) +.TP +.IR /proc/ pid /mountstats " (since Linux 2.6.17)" +This file exports information (statistics, configuration information) +about the mounts in the process's mount namespace (see +.BR mount_namespaces (7)). +Lines in this file have the form: +.IP +.in +4n +.EX +device /dev/sda7 mounted on /home with fstype ext3 [stats] +( 1 ) ( 2 ) (3 ) ( 4 ) +.EE +.in +.IP +The fields in each line are: +.RS 7 +.TP 5 +(1) +The name of the mounted device +(or "nodevice" if there is no corresponding device). +.TP +(2) +The mount point within the filesystem tree. +.TP +(3) +The filesystem type. +.TP +(4) +Optional statistics and configuration information. +Currently (as at Linux 2.6.26), only NFS filesystems export +information via this field. +.RE +.IP +This file is readable only by the owner of the process. +.TP +.IR /proc/ pid /net " (since Linux 2.6.25)" +See the description of +.IR /proc/net . +.TP +.IR /proc/ pid /ns/ " (since Linux 3.0)" +.\" See commit 6b4e306aa3dc94a0545eb9279475b1ab6209a31f +This is a subdirectory containing one entry for each namespace that +supports being manipulated by +.BR setns (2). +For more information, see +.BR namespaces (7). +.TP +.IR /proc/ pid /numa_maps " (since Linux 2.6.14)" +See +.BR numa (7). +.TP +.IR /proc/ pid /oom_adj " (since Linux 2.6.11)" +This file can be used to adjust the score used to select which process +should be killed in an out-of-memory (OOM) situation. +The kernel uses this value for a bit-shift operation of the process's +.I oom_score +value: +valid values are in the range \-16 to +15, +plus the special value \-17, +which disables OOM-killing altogether for this process. +A positive score increases the likelihood of this +process being killed by the OOM-killer; +a negative score decreases the likelihood. +.IP +The default value for this file is 0; +a new process inherits its parent's +.I oom_adj +setting. +A process must be privileged +.RB ( CAP_SYS_RESOURCE ) +to update this file, +although a process can always increase its own +.I oom_adj +setting (since Linux 2.6.20). +.IP +Since Linux 2.6.36, use of this file is deprecated in favor of +.IR /proc/ pid /oom_score_adj , +and finally removed in Linux 3.7. +.TP +.IR /proc/ pid /oom_score " (since Linux 2.6.11)" +.\" See mm/oom_kill.c::badness() before Linux 2.6.36 sources +.\" See mm/oom_kill.c::oom_badness() after Linux 2.6.36 +.\" commit a63d83f427fbce97a6cea0db2e64b0eb8435cd10 +This file displays the current score that the kernel gives to +this process for the purpose of selecting a process +for the OOM-killer. +A higher score means that the process is more likely to be +selected by the OOM-killer. +The basis for this score is the amount of memory used by the process, +with increases (+) or decreases (\-) for factors including: +.\" See mm/oom_kill.c::badness() before Linux 2.6.36 sources +.\" See mm/oom_kill.c::oom_badness() after Linux 2.6.36 +.\" commit a63d83f427fbce97a6cea0db2e64b0eb8435cd10 +.RS +.IP \[bu] 3 +whether the process is privileged (\-). +.\" More precisely, if it has CAP_SYS_ADMIN or (pre 2.6.36) CAP_SYS_RESOURCE +.RE +.IP +Before Linux 2.6.36 +the following factors were also used in the calculation of oom_score: +.RS +.IP \[bu] 3 +whether the process creates a lot of children using +.BR fork (2) +(+); +.IP \[bu] +whether the process has been running a long time, +or has used a lot of CPU time (\-); +.IP \[bu] +whether the process has a low nice value (i.e., > 0) (+); and +.IP \[bu] +whether the process is making direct hardware access (\-). +.\" More precisely, if it has CAP_SYS_RAWIO +.RE +.IP +The +.I oom_score +also reflects the adjustment specified by the +.I oom_score_adj +or +.I oom_adj +setting for the process. +.TP +.IR /proc/ pid /oom_score_adj " (since Linux 2.6.36)" +.\" Text taken from Linux 3.7 Documentation/filesystems/proc.txt +This file can be used to adjust the badness heuristic used to select which +process gets killed in out-of-memory conditions. +.IP +The badness heuristic assigns a value to each candidate task ranging from 0 +(never kill) to 1000 (always kill) to determine which process is targeted. +The units are roughly a proportion along that range of +allowed memory the process may allocate from, +based on an estimation of its current memory and swap use. +For example, if a task is using all allowed memory, +its badness score will be 1000. +If it is using half of its allowed memory, its score will be 500. +.IP +There is an additional factor included in the badness score: root +processes are given 3% extra memory over other tasks. +.IP +The amount of "allowed" memory depends on the context +in which the OOM-killer was called. +If it is due to the memory assigned to the allocating task's cpuset +being exhausted, +the allowed memory represents the set of mems assigned to that +cpuset (see +.BR cpuset (7)). +If it is due to a mempolicy's node(s) being exhausted, +the allowed memory represents the set of mempolicy nodes. +If it is due to a memory limit (or swap limit) being reached, +the allowed memory is that configured limit. +Finally, if it is due to the entire system being out of memory, the +allowed memory represents all allocatable resources. +.IP +The value of +.I oom_score_adj +is added to the badness score before it +is used to determine which task to kill. +Acceptable values range from \-1000 +(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). +This allows user space to control the preference for OOM-killing, +ranging from always preferring a certain +task or completely disabling it from OOM-killing. +The lowest possible value, \-1000, is +equivalent to disabling OOM-killing entirely for that task, +since it will always report a badness score of 0. +.IP +Consequently, it is very simple for user space to define +the amount of memory to consider for each task. +Setting an +.I oom_score_adj +value of +500, for example, +is roughly equivalent to allowing the remainder of tasks sharing the +same system, cpuset, mempolicy, or memory controller resources +to use at least 50% more memory. +A value of \-500, on the other hand, would be roughly +equivalent to discounting 50% of the task's +allowed memory from being considered as scoring against the task. +.IP +For backward compatibility with previous kernels, +.IR /proc/ pid /oom_adj +can still be used to tune the badness score. +Its value is +scaled linearly with +.IR oom_score_adj . +.IP +Writing to +.IR /proc/ pid /oom_score_adj +or +.IR /proc/ pid /oom_adj +will change the other with its scaled value. +.IP +The +.BR choom (1) +program provides a command-line interface for adjusting the +.I oom_score_adj +value of a running process or a newly executed command. +.TP +.IR /proc/ pid /pagemap " (since Linux 2.6.25)" +This file shows the mapping of each of the process's virtual pages +into physical page frames or swap area. +It contains one 64-bit value for each virtual page, +with the bits set as follows: +.RS +.TP +63 +If set, the page is present in RAM. +.TP +62 +If set, the page is in swap space +.TP +61 (since Linux 3.5) +The page is a file-mapped page or a shared anonymous page. +.TP +60\[en]58 (since Linux 3.11) +Zero +.\" Not quite true; see commit 541c237c0923f567c9c4cabb8a81635baadc713f +.TP +57 (since Linux 5.14) +If set, the page is write-protected through +.BR userfaultfd (2). +.TP +56 (since Linux 4.2) +.\" commit 77bb499bb60f4b79cca7d139c8041662860fcf87 +.\" commit 83b4b0bb635eee2b8e075062e4e008d1bc110ed7 +The page is exclusively mapped. +.TP +55 (since Linux 3.11) +PTE is soft-dirty +(see the kernel source file +.IR Documentation/admin\-guide/mm/soft\-dirty.rst ). +.TP +54\[en]0 +If the page is present in RAM (bit 63), then these bits +provide the page frame number, which can be used to index +.I /proc/kpageflags +and +.IR /proc/kpagecount . +If the page is present in swap (bit 62), +then bits 4\[en]0 give the swap type, and bits 54\[en]5 encode the swap offset. +.RE +.IP +Before Linux 3.11, bits 60\[en]55 were +used to encode the base-2 log of the page size. +.IP +To employ +.IR /proc/ pid /pagemap +efficiently, use +.IR /proc/ pid /maps +to determine which areas of memory are actually mapped and seek +to skip over unmapped regions. +.IP +The +.IR /proc/ pid /pagemap +file is present only if the +.B CONFIG_PROC_PAGE_MONITOR +kernel configuration option is enabled. +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /personality " (since Linux 2.6.28)" +.\" commit 478307230810d7e2a753ed220db9066dfdf88718 +This read-only file exposes the process's execution domain, as set by +.BR personality (2). +The value is displayed in hexadecimal notation. +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_ATTACH_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /root +UNIX and Linux support the idea of a per-process root of the +filesystem, set by the +.BR chroot (2) +system call. +This file is a symbolic link that points to the process's +root directory, and behaves in the same way as +.IR exe , +and +.IR fd/* . +.IP +Note however that this file is not merely a symbolic link. +It provides the same view of the filesystem (including namespaces and the +set of per-process mounts) as the process itself. +An example illustrates this point. +In one terminal, we start a shell in new user and mount namespaces, +and in that shell we create some new mounts: +.IP +.in +4n +.EX +$ \fBPS1=\[aq]sh1# \[aq] unshare \-Urnm\fP +sh1# \fBmount \-t tmpfs tmpfs /etc\fP # Mount empty tmpfs at /etc +sh1# \fBmount \-\-bind /usr /dev\fP # Mount /usr at /dev +sh1# \fBecho $$\fP +27123 +.EE +.in +.IP +In a second terminal window, in the initial mount namespace, +we look at the contents of the corresponding mounts in +the initial and new namespaces: +.IP +.in +4n +.EX +$ \fBPS1=\[aq]sh2# \[aq] sudo sh\fP +sh2# \fBls /etc | wc \-l\fP # In initial NS +309 +sh2# \fBls /proc/27123/root/etc | wc \-l\fP # /etc in other NS +0 # The empty tmpfs dir +sh2# \fBls /dev | wc \-l\fP # In initial NS +205 +sh2# \fBls /proc/27123/root/dev | wc \-l\fP # /dev in other NS +11 # Actually bind + # mounted to /usr +sh2# \fBls /usr | wc \-l\fP # /usr in initial NS +11 +.EE +.in +.IP +.\" The following was still true as at kernel 2.6.13 +In a multithreaded process, the contents of the +.IR /proc/ pid /root +symbolic link are not available if the main thread has already terminated +(typically by calling +.BR pthread_exit (3)). +.IP +Permission to dereference or read +.RB ( readlink (2)) +this symbolic link is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /projid_map " (since Linux 3.7)" +.\" commit f76d207a66c3a53defea67e7d36c3eb1b7d6d61d +See +.BR user_namespaces (7). +.TP +.IR /proc/ pid /seccomp " (Linux 2.6.12 to Linux 2.6.22)" +This file can be used to read and change the process's +secure computing (seccomp) mode setting. +It contains the value 0 if the process is not in seccomp mode, +and 1 if the process is in strict seccomp mode (see +.BR seccomp (2)). +Writing 1 to this file places the process irreversibly in strict seccomp mode. +(Further attempts to write to the file fail with the +.B EPERM +error.) +.IP +In Linux 2.6.23, +this file went away, to be replaced by the +.BR prctl (2) +.B PR_GET_SECCOMP +and +.B PR_SET_SECCOMP +operations (and later by +.BR seccomp (2) +and the +.I Seccomp +field in +.IR /proc/ pid /status ). +.\" FIXME Describe /proc/[pid]/sessionid +.\" commit 1e0bd7550ea9cf474b1ad4c6ff5729a507f75fdc +.\" CONFIG_AUDITSYSCALL +.\" Added in Linux 2.6.25; read-only; only readable by real UID +.\" +.\" FIXME Describe /proc/[pid]/sched +.\" Added in Linux 2.6.23 +.\" CONFIG_SCHED_DEBUG, and additional fields if CONFIG_SCHEDSTATS +.\" Displays various scheduling parameters +.\" This file can be written, to reset stats +.\" The set of fields exposed by this file have changed +.\" significantly over time. +.\" commit 43ae34cb4cd650d1eb4460a8253a8e747ba052ac +.\" +.\" FIXME Describe /proc/[pid]/schedstats and +.\" /proc/[pid]/task/[tid]/schedstats +.\" Added in Linux 2.6.9 +.\" CONFIG_SCHEDSTATS +.TP +.IR /proc/ pid /setgroups " (since Linux 3.19)" +See +.BR user_namespaces (7). +.TP +.IR /proc/ pid /smaps " (since Linux 2.6.14)" +This file shows memory consumption for each of the process's mappings. +(The +.BR pmap (1) +command displays similar information, +in a form that may be easier for parsing.) +For each mapping there is a series of lines such as the following: +.IP +.in +4n +.EX +00400000\-0048a000 r\-xp 00000000 fd:03 960637 /bin/bash +Size: 552 kB +Rss: 460 kB +Pss: 100 kB +Shared_Clean: 452 kB +Shared_Dirty: 0 kB +Private_Clean: 8 kB +Private_Dirty: 0 kB +Referenced: 460 kB +Anonymous: 0 kB +AnonHugePages: 0 kB +ShmemHugePages: 0 kB +ShmemPmdMapped: 0 kB +Swap: 0 kB +KernelPageSize: 4 kB +MMUPageSize: 4 kB +Locked: 0 kB +ProtectionKey: 0 +VmFlags: rd ex mr mw me dw +.EE +.in +.IP +The first of these lines shows the same information as is displayed +for the mapping in +.IR /proc/ pid /maps . +The following lines show the size of the mapping, +the amount of the mapping that is currently resident in RAM ("Rss"), +the process's proportional share of this mapping ("Pss"), +the number of clean and dirty shared pages in the mapping, +and the number of clean and dirty private pages in the mapping. +"Referenced" indicates the amount of memory currently marked as +referenced or accessed. +"Anonymous" shows the amount of memory +that does not belong to any file. +"Swap" shows how much +would-be-anonymous memory is also used, but out on swap. +.IP +The "KernelPageSize" line (available since Linux 2.6.29) +is the page size used by the kernel to back the virtual memory area. +This matches the size used by the MMU in the majority of cases. +However, one counter-example occurs on PPC64 kernels +whereby a kernel using 64 kB as a base page size may still use 4 kB +pages for the MMU on older processors. +To distinguish the two attributes, the "MMUPageSize" line +(also available since Linux 2.6.29) +reports the page size used by the MMU. +.IP +The "Locked" indicates whether the mapping is locked in memory +or not. +.IP +The "ProtectionKey" line (available since Linux 4.9, on x86 only) +contains the memory protection key (see +.BR pkeys (7)) +associated with the virtual memory area. +This entry is present only if the kernel was built with the +.B CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS +configuration option (since Linux 4.6). +.IP +The "VmFlags" line (available since Linux 3.8) +represents the kernel flags associated with the virtual memory area, +encoded using the following two-letter codes: +.RS +.IP +.TS +l l l. +rd - readable +wr - writable +ex - executable +sh - shared +mr - may read +mw - may write +me - may execute +ms - may share +gd - stack segment grows down +pf - pure PFN range +dw - disabled write to the mapped file +lo - pages are locked in memory +io - memory mapped I/O area +sr - sequential read advise provided +rr - random read advise provided +dc - do not copy area on fork +de - do not expand area on remapping +ac - area is accountable +nr - swap space is not reserved for the area +ht - area uses huge tlb pages +sf - perform synchronous page faults (since Linux 4.15) +nl - non-linear mapping (removed in Linux 4.0) +ar - architecture specific flag +wf - wipe on fork (since Linux 4.14) +dd - do not include area into core dump +sd - soft-dirty flag (since Linux 3.13) +mm - mixed map area +hg - huge page advise flag +nh - no-huge page advise flag +mg - mergeable advise flag +um - userfaultfd missing pages tracking (since Linux 4.3) +uw - userfaultfd wprotect pages tracking (since Linux 4.3) +.TE +.RE +.IP +The +.IR /proc/ pid /smaps +file is present only if the +.B CONFIG_PROC_PAGE_MONITOR +kernel configuration option is enabled. +.TP +.IR /proc/ pid /stack " (since Linux 2.6.29)" +.\" 2ec220e27f5040aec1e88901c1b6ea3d135787ad +This file provides a symbolic trace of the function calls in this +process's kernel stack. +This file is provided only if the kernel was built with the +.B CONFIG_STACKTRACE +configuration option. +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_ATTACH_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /stat +Status information about the process. +This is used by +.BR ps (1). +It is defined in the kernel source file +.IR fs/proc/array.c "." +.IP +The fields, in order, with their proper +.BR scanf (3) +format specifiers, are listed below. +Whether or not certain of these fields display valid information is governed by +a ptrace access mode +.BR PTRACE_MODE_READ_FSCREDS " | " PTRACE_MODE_NOAUDIT +check (refer to +.BR ptrace (2)). +If the check denies access, then the field value is displayed as 0. +The affected fields are indicated with the marking [PT]. +.RS +.TP +(1) \fIpid\fP \ %d +.br +The process ID. +.TP +(2) \fIcomm\fP \ %s +The filename of the executable, in parentheses. +Strings longer than +.B TASK_COMM_LEN +(16) characters (including the terminating null byte) are silently truncated. +This is visible whether or not the executable is swapped out. +.TP +(3) \fIstate\fP \ %c +One of the following characters, indicating process state: +.RS +.TP +R +Running +.TP +S +Sleeping in an interruptible wait +.TP +D +Waiting in uninterruptible +disk sleep +.TP +Z +Zombie +.TP +T +Stopped (on a signal) or (before Linux 2.6.33) trace stopped +.TP +t +.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29 +Tracing stop (Linux 2.6.33 onward) +.TP +W +Paging (only before Linux 2.6.0) +.TP +X +Dead (from Linux 2.6.0 onward) +.TP +x +.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29 +Dead (Linux 2.6.33 to +.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457 +3.13 only) +.TP +K +.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29 +Wakekill (Linux 2.6.33 to +.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457 +3.13 only) +.TP +W +.\" commit 44d90df6b757c59651ddd55f1a84f28132b50d29 +Waking (Linux 2.6.33 to +.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457 +3.13 only) +.TP +P +.\" commit f2530dc71cf0822f90bb63ea4600caaef33a66bb +Parked (Linux 3.9 to +.\" commit 74e37200de8e9c4e09b70c21c3f13c2071e77457 +3.13 only) +.TP +I +.\" commit 06eb61844d841d0032a9950ce7f8e783ee49c0d0 +Idle (Linux 4.14 onward) +.RE +.TP +(4) \fIppid\fP \ %d +The PID of the parent of this process. +.TP +(5) \fIpgrp\fP \ %d +The process group ID of the process. +.TP +(6) \fIsession\fP \ %d +The session ID of the process. +.TP +(7) \fItty_nr\fP \ %d +The controlling terminal of the process. +(The minor device number is contained in the combination of bits +31 to 20 and 7 to 0; +the major device number is in bits 15 to 8.) +.TP +(8) \fItpgid\fP \ %d +.\" This field and following, up to and including wchan added 0.99.1 +The ID of the foreground process group of the controlling +terminal of the process. +.TP +(9) \fIflags\fP \ %u +The kernel flags word of the process. +For bit meanings, +see the PF_* defines in the Linux kernel source file +.IR include/linux/sched.h . +Details depend on the kernel version. +.IP +The format for this field was %lu before Linux 2.6. +.TP +(10) \fIminflt\fP \ %lu +The number of minor faults the process has made which have not +required loading a memory page from disk. +.TP +(11) \fIcminflt\fP \ %lu +The number of minor faults that the process's +waited-for children have made. +.TP +(12) \fImajflt\fP \ %lu +The number of major faults the process has made which have +required loading a memory page from disk. +.TP +(13) \fIcmajflt\fP \ %lu +The number of major faults that the process's +waited-for children have made. +.TP +(14) \fIutime\fP \ %lu +Amount of time that this process has been scheduled in user mode, +measured in clock ticks (divide by +.IR sysconf(_SC_CLK_TCK) ). +This includes guest time, \fIguest_time\fP +(time spent running a virtual CPU, see below), +so that applications that are not aware of the guest time field +do not lose that time from their calculations. +.TP +(15) \fIstime\fP \ %lu +Amount of time that this process has been scheduled in kernel mode, +measured in clock ticks (divide by +.IR sysconf(_SC_CLK_TCK) ). +.TP +(16) \fIcutime\fP \ %ld +Amount of time that this process's +waited-for children have been scheduled in user mode, +measured in clock ticks (divide by +.IR sysconf(_SC_CLK_TCK) ). +(See also +.BR times (2).) +This includes guest time, \fIcguest_time\fP +(time spent running a virtual CPU, see below). +.TP +(17) \fIcstime\fP \ %ld +Amount of time that this process's +waited-for children have been scheduled in kernel mode, +measured in clock ticks (divide by +.IR sysconf(_SC_CLK_TCK) ). +.TP +(18) \fIpriority\fP \ %ld +(Explanation for Linux 2.6) +For processes running a real-time scheduling policy +.RI ( policy +below; see +.BR sched_setscheduler (2)), +this is the negated scheduling priority, minus one; +that is, a number in the range \-2 to \-100, +corresponding to real-time priorities 1 to 99. +For processes running under a non-real-time scheduling policy, +this is the raw nice value +.RB ( setpriority (2)) +as represented in the kernel. +The kernel stores nice values as numbers +in the range 0 (high) to 39 (low), +corresponding to the user-visible nice range of \-20 to 19. +.IP +Before Linux 2.6, this was a scaled value based on +the scheduler weighting given to this process. +.\" And back in Linux 1.2 days things were different again. +.TP +(19) \fInice\fP \ %ld +The nice value (see +.BR setpriority (2)), +a value in the range 19 (low priority) to \-20 (high priority). +.\" Back in Linux 1.2 days things were different. +.\" .TP +.\" \fIcounter\fP %ld +.\" The current maximum size in jiffies of the process's next timeslice, +.\" or what is currently left of its current timeslice, if it is the +.\" currently running process. +.\" .TP +.\" \fItimeout\fP %u +.\" The time in jiffies of the process's next timeout. +.\" timeout was removed sometime around 2.1/2.2 +.TP +(20) \fInum_threads\fP \ %ld +Number of threads in this process (since Linux 2.6). +Before Linux 2.6, this field was hard coded to 0 as a placeholder +for an earlier removed field. +.TP +(21) \fIitrealvalue\fP \ %ld +The time in jiffies before the next +.B SIGALRM +is sent to the process due to an interval timer. +Since Linux 2.6.17, this field is no longer maintained, +and is hard coded as 0. +.TP +(22) \fIstarttime\fP \ %llu +The time the process started after system boot. +Before Linux 2.6, this value was expressed in jiffies. +Since Linux 2.6, the value is expressed in clock ticks (divide by +.IR sysconf(_SC_CLK_TCK) ). +.IP +The format for this field was %lu before Linux 2.6. +.TP +(23) \fIvsize\fP \ %lu +Virtual memory size in bytes. +.TP +(24) \fIrss\fP \ %ld +Resident Set Size: number of pages the process has in real memory. +This is just the pages which +count toward text, data, or stack space. +This does not include pages +which have not been demand-loaded in, or which are swapped out. +This value is inaccurate; see +.IR /proc/ pid /statm +below. +.TP +(25) \fIrsslim\fP \ %lu +Current soft limit in bytes on the rss of the process; +see the description of +.B RLIMIT_RSS +in +.BR getrlimit (2). +.TP +(26) \fIstartcode\fP \ %lu \ [PT] +The address above which program text can run. +.TP +(27) \fIendcode\fP \ %lu \ [PT] +The address below which program text can run. +.TP +(28) \fIstartstack\fP \ %lu \ [PT] +The address of the start (i.e., bottom) of the stack. +.TP +(29) \fIkstkesp\fP \ %lu \ [PT] +The current value of ESP (stack pointer), as found in the +kernel stack page for the process. +.TP +(30) \fIkstkeip\fP \ %lu \ [PT] +The current EIP (instruction pointer). +.TP +(31) \fIsignal\fP \ %lu +The bitmap of pending signals, displayed as a decimal number. +Obsolete, because it does not provide information on real-time signals; use +.IR /proc/ pid /status +instead. +.TP +(32) \fIblocked\fP \ %lu +The bitmap of blocked signals, displayed as a decimal number. +Obsolete, because it does not provide information on real-time signals; use +.IR /proc/ pid /status +instead. +.TP +(33) \fIsigignore\fP \ %lu +The bitmap of ignored signals, displayed as a decimal number. +Obsolete, because it does not provide information on real-time signals; use +.IR /proc/ pid /status +instead. +.TP +(34) \fIsigcatch\fP \ %lu +The bitmap of caught signals, displayed as a decimal number. +Obsolete, because it does not provide information on real-time signals; use +.IR /proc/ pid /status +instead. +.TP +(35) \fIwchan\fP \ %lu \ [PT] +This is the "channel" in which the process is waiting. +It is the address of a location in the kernel where the process is sleeping. +The corresponding symbolic name can be found in +.IR /proc/ pid /wchan . +.TP +(36) \fInswap\fP \ %lu +.\" nswap was added in Linux 2.0 +Number of pages swapped (not maintained). +.TP +(37) \fIcnswap\fP \ %lu +.\" cnswap was added in Linux 2.0 +Cumulative \fInswap\fP for child processes (not maintained). +.TP +(38) \fIexit_signal\fP \ %d \ (since Linux 2.1.22) +Signal to be sent to parent when we die. +.TP +(39) \fIprocessor\fP \ %d \ (since Linux 2.2.8) +CPU number last executed on. +.TP +(40) \fIrt_priority\fP \ %u \ (since Linux 2.5.19) +Real-time scheduling priority, a number in the range 1 to 99 for +processes scheduled under a real-time policy, +or 0, for non-real-time processes (see +.BR sched_setscheduler (2)). +.TP +(41) \fIpolicy\fP \ %u \ (since Linux 2.5.19) +Scheduling policy (see +.BR sched_setscheduler (2)). +Decode using the SCHED_* constants in +.IR linux/sched.h . +.IP +The format for this field was %lu before Linux 2.6.22. +.TP +(42) \fIdelayacct_blkio_ticks\fP \ %llu \ (since Linux 2.6.18) +Aggregated block I/O delays, measured in clock ticks (centiseconds). +.TP +(43) \fIguest_time\fP \ %lu \ (since Linux 2.6.24) +Guest time of the process (time spent running a virtual CPU +for a guest operating system), measured in clock ticks (divide by +.IR sysconf(_SC_CLK_TCK) ). +.TP +(44) \fIcguest_time\fP \ %ld \ (since Linux 2.6.24) +Guest time of the process's children, measured in clock ticks (divide by +.IR sysconf(_SC_CLK_TCK) ). +.TP +(45) \fIstart_data\fP \ %lu \ (since Linux 3.3) \ [PT] +.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff +Address above which program initialized and +uninitialized (BSS) data are placed. +.TP +(46) \fIend_data\fP \ %lu \ (since Linux 3.3) \ [PT] +.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff +Address below which program initialized and +uninitialized (BSS) data are placed. +.TP +(47) \fIstart_brk\fP \ %lu \ (since Linux 3.3) \ [PT] +.\" commit b3f7f573a20081910e34e99cbc91831f4f02f1ff +Address above which program heap can be expanded with +.BR brk (2). +.TP +(48) \fIarg_start\fP \ %lu \ (since Linux 3.5) \ [PT] +.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3 +Address above which program command-line arguments +.RI ( argv ) +are placed. +.TP +(49) \fIarg_end\fP \ %lu \ (since Linux 3.5) \ [PT] +.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3 +Address below program command-line arguments +.RI ( argv ) +are placed. +.TP +(50) \fIenv_start\fP \ %lu \ (since Linux 3.5) \ [PT] +.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3 +Address above which program environment is placed. +.TP +(51) \fIenv_end\fP \ %lu \ (since Linux 3.5) \ [PT] +.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3 +Address below which program environment is placed. +.TP +(52) \fIexit_code\fP \ %d \ (since Linux 3.5) \ [PT] +.\" commit 5b172087f99189416d5f47fd7ab5e6fb762a9ba3 +The thread's exit status in the form reported by +.BR waitpid (2). +.RE +.TP +.IR /proc/ pid /statm +Provides information about memory usage, measured in pages. +The columns are: +.IP +.in +4n +.EX +size (1) total program size + (same as VmSize in \fI/proc/\fPpid\fI/status\fP) +resident (2) resident set size + (inaccurate; same as VmRSS in \fI/proc/\fPpid\fI/status\fP) +shared (3) number of resident shared pages + (i.e., backed by a file) + (inaccurate; same as RssFile+RssShmem in + \fI/proc/\fPpid\fI/status\fP) +text (4) text (code) +.\" (not including libs; broken, includes data segment) +lib (5) library (unused since Linux 2.6; always 0) +data (6) data + stack +.\" (including libs; broken, includes library text) +dt (7) dirty pages (unused since Linux 2.6; always 0) +.EE +.in +.IP +.\" See SPLIT_RSS_COUNTING in the kernel. +.\" Inaccuracy is bounded by TASK_RSS_EVENTS_THRESH. +Some of these values are inaccurate because +of a kernel-internal scalability optimization. +If accurate values are required, use +.IR /proc/ pid /smaps +or +.IR /proc/ pid /smaps_rollup +instead, which are much slower but provide accurate, detailed information. +.TP +.IR /proc/ pid /status +Provides much of the information in +.IR /proc/ pid /stat +and +.IR /proc/ pid /statm +in a format that's easier for humans to parse. +Here's an example: +.IP +.in +4n +.EX +.RB "$" " cat /proc/$$/status" +Name: bash +Umask: 0022 +State: S (sleeping) +Tgid: 17248 +Ngid: 0 +Pid: 17248 +PPid: 17200 +TracerPid: 0 +Uid: 1000 1000 1000 1000 +Gid: 100 100 100 100 +FDSize: 256 +Groups: 16 33 100 +NStgid: 17248 +NSpid: 17248 +NSpgid: 17248 +NSsid: 17200 +VmPeak: 131168 kB +VmSize: 131168 kB +VmLck: 0 kB +VmPin: 0 kB +VmHWM: 13484 kB +VmRSS: 13484 kB +RssAnon: 10264 kB +RssFile: 3220 kB +RssShmem: 0 kB +VmData: 10332 kB +VmStk: 136 kB +VmExe: 992 kB +VmLib: 2104 kB +VmPTE: 76 kB +VmPMD: 12 kB +VmSwap: 0 kB +HugetlbPages: 0 kB # 4.4 +CoreDumping: 0 # 4.15 +Threads: 1 +SigQ: 0/3067 +SigPnd: 0000000000000000 +ShdPnd: 0000000000000000 +SigBlk: 0000000000010000 +SigIgn: 0000000000384004 +SigCgt: 000000004b813efb +CapInh: 0000000000000000 +CapPrm: 0000000000000000 +CapEff: 0000000000000000 +CapBnd: ffffffffffffffff +CapAmb: 0000000000000000 +NoNewPrivs: 0 +Seccomp: 0 +Speculation_Store_Bypass: vulnerable +Cpus_allowed: 00000001 +Cpus_allowed_list: 0 +Mems_allowed: 1 +Mems_allowed_list: 0 +voluntary_ctxt_switches: 150 +nonvoluntary_ctxt_switches: 545 +.EE +.in +.IP +The fields are as follows: +.RS +.TP +.I Name +Command run by this process. +Strings longer than +.B TASK_COMM_LEN +(16) characters (including the terminating null byte) are silently truncated. +.TP +.I Umask +Process umask, expressed in octal with a leading zero; see +.BR umask (2). +(Since Linux 4.7.) +.TP +.I State +Current state of the process. +One of +"R (running)", +"S (sleeping)", +"D (disk sleep)", +"T (stopped)", +"t (tracing stop)", +"Z (zombie)", +or +"X (dead)". +.TP +.I Tgid +Thread group ID (i.e., Process ID). +.TP +.I Ngid +NUMA group ID (0 if none; since Linux 3.13). +.TP +.I Pid +Thread ID (see +.BR gettid (2)). +.TP +.I PPid +PID of parent process. +.TP +.I TracerPid +PID of process tracing this process (0 if not being traced). +.TP +.IR Uid ", " Gid +Real, effective, saved set, and filesystem UIDs (GIDs). +.TP +.I FDSize +Number of file descriptor slots currently allocated. +.TP +.I Groups +Supplementary group list. +.TP +.I NStgid +Thread group ID (i.e., PID) in each of the PID namespaces of which +.I pid +is a member. +The leftmost entry shows the value with respect to the PID namespace +of the process that mounted this procfs (or the root namespace +if mounted by the kernel), +followed by the value in successively nested inner namespaces. +.\" commit e4bc33245124db69b74a6d853ac76c2976f472d5 +(Since Linux 4.1.) +.TP +.I NSpid +Thread ID in each of the PID namespaces of which +.I pid +is a member. +The fields are ordered as for +.IR NStgid . +(Since Linux 4.1.) +.TP +.I NSpgid +Process group ID in each of the PID namespaces of which +.I pid +is a member. +The fields are ordered as for +.IR NStgid . +(Since Linux 4.1.) +.TP +.I NSsid +descendant namespace session ID hierarchy +Session ID in each of the PID namespaces of which +.I pid +is a member. +The fields are ordered as for +.IR NStgid . +(Since Linux 4.1.) +.TP +.I VmPeak +Peak virtual memory size. +.TP +.I VmSize +Virtual memory size. +.TP +.I VmLck +Locked memory size (see +.BR mlock (2)). +.TP +.I VmPin +Pinned memory size +.\" commit bc3e53f682d93df677dbd5006a404722b3adfe18 +(since Linux 3.2). +These are pages that can't be moved because something needs to +directly access physical memory. +.TP +.I VmHWM +Peak resident set size ("high water mark"). +This value is inaccurate; see +.IR /proc/ pid /statm +above. +.TP +.I VmRSS +Resident set size. +Note that the value here is the sum of +.IR RssAnon , +.IR RssFile , +and +.IR RssShmem . +This value is inaccurate; see +.IR /proc/ pid /statm +above. +.TP +.I RssAnon +Size of resident anonymous memory. +.\" commit bf9683d6990589390b5178dafe8fd06808869293 +(since Linux 4.5). +This value is inaccurate; see +.IR /proc/ pid /statm +above. +.TP +.I RssFile +Size of resident file mappings. +.\" commit bf9683d6990589390b5178dafe8fd06808869293 +(since Linux 4.5). +This value is inaccurate; see +.IR /proc/ pid /statm +above. +.TP +.I RssShmem +Size of resident shared memory (includes System V shared memory, +mappings from +.BR tmpfs (5), +and shared anonymous mappings). +.\" commit bf9683d6990589390b5178dafe8fd06808869293 +(since Linux 4.5). +.TP +.IR VmData ", " VmStk ", " VmExe +Size of data, stack, and text segments. +This value is inaccurate; see +.IR /proc/ pid /statm +above. +.TP +.I VmLib +Shared library code size. +.TP +.I VmPTE +Page table entries size (since Linux 2.6.10). +.TP +.I VmPMD +.\" commit dc6c9a35b66b520cf67e05d8ca60ebecad3b0479 +Size of second-level page tables (added in Linux 4.0; removed in Linux 4.15). +.TP +.I VmSwap +.\" commit b084d4353ff99d824d3bc5a5c2c22c70b1fba722 +Swapped-out virtual memory size by anonymous private pages; +shmem swap usage is not included (since Linux 2.6.34). +This value is inaccurate; see +.IR /proc/ pid /statm +above. +.TP +.I HugetlbPages +Size of hugetlb memory portions +.\" commit 5d317b2b6536592a9b51fe65faed43d65ca9158e +(since Linux 4.4). +.TP +.I CoreDumping +Contains the value 1 if the process is currently dumping core, +and 0 if it is not +.\" commit c643401218be0f4ab3522e0c0a63016596d6e9ca +(since Linux 4.15). +This information can be used by a monitoring process to avoid killing +a process that is currently dumping core, +which could result in a corrupted core dump file. +.TP +.I Threads +Number of threads in process containing this thread. +.TP +.I SigQ +This field contains two slash-separated numbers that relate to +queued signals for the real user ID of this process. +The first of these is the number of currently queued +signals for this real user ID, and the second is the +resource limit on the number of queued signals for this process +(see the description of +.B RLIMIT_SIGPENDING +in +.BR getrlimit (2)). +.TP +.IR SigPnd ", " ShdPnd +Mask (expressed in hexadecimal) +of signals pending for thread and for process as a whole (see +.BR pthreads (7) +and +.BR signal (7)). +.TP +.IR SigBlk ", " SigIgn ", " SigCgt +Masks (expressed in hexadecimal) +indicating signals being blocked, ignored, and caught (see +.BR signal (7)). +.TP +.IR CapInh ", " CapPrm ", " CapEff +Masks (expressed in hexadecimal) +of capabilities enabled in inheritable, permitted, and effective sets +(see +.BR capabilities (7)). +.TP +.I CapBnd +Capability bounding set, expressed in hexadecimal +(since Linux 2.6.26, see +.BR capabilities (7)). +.TP +.I CapAmb +Ambient capability set, expressed in hexadecimal +(since Linux 4.3, see +.BR capabilities (7)). +.TP +.I NoNewPrivs +.\" commit af884cd4a5ae62fcf5e321fecf0ec1014730353d +Value of the +.I no_new_privs +bit +(since Linux 4.10, see +.BR prctl (2)). +.TP +.I Seccomp +.\" commit 2f4b3bf6b2318cfaa177ec5a802f4d8d6afbd816 +Seccomp mode of the process +(since Linux 3.8, see +.BR seccomp (2)). +0 means +.BR SECCOMP_MODE_DISABLED ; +1 means +.BR SECCOMP_MODE_STRICT ; +2 means +.BR SECCOMP_MODE_FILTER . +This field is provided only if the kernel was built with the +.B CONFIG_SECCOMP +kernel configuration option enabled. +.TP +.I Speculation_Store_Bypass +.\" commit fae1fa0fc6cca8beee3ab8ed71d54f9a78fa3f64 +Speculation flaw mitigation state +(since Linux 4.17, see +.BR prctl (2)). +.TP +.I Cpus_allowed +Hexadecimal mask of CPUs on which this process may run +(since Linux 2.6.24, see +.BR cpuset (7)). +.TP +.I Cpus_allowed_list +Same as previous, but in "list format" +(since Linux 2.6.26, see +.BR cpuset (7)). +.TP +.I Mems_allowed +Mask of memory nodes allowed to this process +(since Linux 2.6.24, see +.BR cpuset (7)). +.TP +.I Mems_allowed_list +Same as previous, but in "list format" +(since Linux 2.6.26, see +.BR cpuset (7)). +.TP +.IR voluntary_ctxt_switches ", " nonvoluntary_ctxt_switches +Number of voluntary and involuntary context switches (since Linux 2.6.23). +.RE +.TP +.IR /proc/ pid /syscall " (since Linux 2.6.27)" +.\" commit ebcb67341fee34061430f3367f2e507e52ee051b +This file exposes the system call number and argument registers for the +system call currently being executed by the process, +followed by the values of the stack pointer and program counter registers. +The values of all six argument registers are exposed, +although most system calls use fewer registers. +.IP +If the process is blocked, but not in a system call, +then the file displays \-1 in place of the system call number, +followed by just the values of the stack pointer and program counter. +If process is not blocked, then the file contains just the string "running". +.IP +This file is present only if the kernel was configured with +.BR CONFIG_HAVE_ARCH_TRACEHOOK . +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_ATTACH_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ pid /task " (since Linux 2.6.0)" +.\" Precisely: Linux 2.6.0-test6 +This is a directory that contains one subdirectory +for each thread in the process. +The name of each subdirectory is the numerical thread ID +.RI ( tid ) +of the thread (see +.BR gettid (2)). +.IP +Within each of these subdirectories, there is a set of +files with the same names and contents as under the +.IR /proc/ pid +directories. +For attributes that are shared by all threads, the contents for +each of the files under the +.IR task/ tid +subdirectories will be the same as in the corresponding +file in the parent +.IR /proc/ pid +directory +(e.g., in a multithreaded process, all of the +.IR task/ tid /cwd +files will have the same value as the +.IR /proc/ pid /cwd +file in the parent directory, since all of the threads in a process +share a working directory). +For attributes that are distinct for each thread, +the corresponding files under +.IR task/ tid +may have different values (e.g., various fields in each of the +.IR task/ tid /status +files may be different for each thread), +.\" in particular: "children" :/ +or they might not exist in +.IR /proc/ pid +at all. +.IP +.\" The following was still true as at kernel 2.6.13 +In a multithreaded process, the contents of the +.IR /proc/ pid /task +directory are not available if the main thread has already terminated +(typically by calling +.BR pthread_exit (3)). +.TP +.IR /proc/ pid /task/ tid /children " (since Linux 3.5)" +.\" commit 818411616baf46ceba0cff6f05af3a9b294734f7 +A space-separated list of child tasks of this task. +Each child task is represented by its TID. +.IP +.\" see comments in get_children_pid() in fs/proc/array.c +This option is intended for use by the checkpoint-restore (CRIU) system, +and reliably provides a list of children only if all of the child processes +are stopped or frozen. +It does not work properly if children of the target task exit while +the file is being read! +Exiting children may cause non-exiting children to be omitted from the list. +This makes this interface even more unreliable than classic PID-based +approaches if the inspected task and its children aren't frozen, +and most code should probably not use this interface. +.IP +Until Linux 4.2, the presence of this file was governed by the +.B CONFIG_CHECKPOINT_RESTORE +kernel configuration option. +Since Linux 4.2, +.\" commit 2e13ba54a2682eea24918b87ad3edf70c2cf085b +it is governed by the +.B CONFIG_PROC_CHILDREN +option. +.TP +.IR /proc/ pid /timers " (since Linux 3.10)" +.\" commit 5ed67f05f66c41e39880a6d61358438a25f9fee5 +.\" commit 48f6a7a511ef8823fdff39afee0320092d43a8a0 +A list of the POSIX timers for this process. +Each timer is listed with a line that starts with the string "ID:". +For example: +.IP +.in +4n +.EX +ID: 1 +signal: 60/00007fff86e452a8 +notify: signal/pid.2634 +ClockID: 0 +ID: 0 +signal: 60/00007fff86e452a8 +notify: signal/pid.2634 +ClockID: 1 +.EE +.in +.IP +The lines shown for each timer have the following meanings: +.RS +.TP +.I ID +The ID for this timer. +This is not the same as the timer ID returned by +.BR timer_create (2); +rather, it is the same kernel-internal ID that is available via the +.I si_timerid +field of the +.I siginfo_t +structure (see +.BR sigaction (2)). +.TP +.I signal +This is the signal number that this timer uses to deliver notifications +followed by a slash, and then the +.I sigev_value +value supplied to the signal handler. +Valid only for timers that notify via a signal. +.TP +.I notify +The part before the slash specifies the mechanism +that this timer uses to deliver notifications, +and is one of "thread", "signal", or "none". +Immediately following the slash is either the string "tid" for timers +with +.B SIGEV_THREAD_ID +notification, or "pid" for timers that notify by other mechanisms. +Following the "." is the PID of the process +(or the kernel thread ID of the thread) that will be delivered +a signal if the timer delivers notifications via a signal. +.TP +.I ClockID +This field identifies the clock that the timer uses for measuring time. +For most clocks, this is a number that matches one of the user-space +.B CLOCK_* +constants exposed via +.IR <time.h> . +.B CLOCK_PROCESS_CPUTIME_ID +timers display with a value of \-6 +in this field. +.B CLOCK_THREAD_CPUTIME_ID +timers display with a value of \-2 +in this field. +.RE +.IP +This file is available only when the kernel was configured with +.BR CONFIG_CHECKPOINT_RESTORE . +.TP +.IR /proc/ pid /timerslack_ns " (since Linux 4.6)" +.\" commit da8b44d5a9f8bf26da637b7336508ca534d6b319 +.\" commit 5de23d435e88996b1efe0e2cebe242074ce67c9e +This file exposes the process's "current" timer slack value, +expressed in nanoseconds. +The file is writable, +allowing the process's timer slack value to be changed. +Writing 0 to this file resets the "current" timer slack to the +"default" timer slack value. +For further details, see the discussion of +.B PR_SET_TIMERSLACK +in +.BR prctl (2). +.IP +Initially, +permission to access this file was governed by a ptrace access mode +.B PTRACE_MODE_ATTACH_FSCREDS +check (see +.BR ptrace (2)). +However, this was subsequently deemed too strict a requirement +(and had the side effect that requiring a process to have the +.B CAP_SYS_PTRACE +capability would also allow it to view and change any process's memory). +Therefore, since Linux 4.9, +.\" commit 7abbaf94049914f074306d960b0f968ffe52e59f +only the (weaker) +.B CAP_SYS_NICE +capability is required to access this file. +.TP +.IR /proc/ pid /uid_map " (since Linux 3.5)" +See +.BR user_namespaces (7). +.TP +.IR /proc/ pid /wchan " (since Linux 2.6.0)" +The symbolic name corresponding to the location +in the kernel where the process is sleeping. +.IP +Permission to access this file is governed by a ptrace access mode +.B PTRACE_MODE_READ_FSCREDS +check; see +.BR ptrace (2). +.TP +.IR /proc/ tid +There is a numerical subdirectory for each running thread +that is not a thread group leader +(i.e., a thread whose thread ID is not the same as its process ID); +the subdirectory is named by the thread ID. +Each one of these subdirectories contains files and subdirectories +exposing information about the thread with the thread ID +.IR tid . +The contents of these directories are the same as the corresponding +.IR /proc/ pid /task/ tid +directories. +.IP +The +.IR /proc/ tid +subdirectories are +.I not +visible when iterating through +.I /proc +with +.BR getdents (2) +(and thus are +.I not +visible when one uses +.BR ls (1) +to view the contents of +.IR /proc ). +However, the pathnames of these directories are visible to +(i.e., usable as arguments in) +system calls that operate on pathnames. +.TP +.I /proc/apm +Advanced power management version and battery information when +.B CONFIG_APM +is defined at kernel compilation time. +.TP +.I /proc/buddyinfo +This file contains information which is used for diagnosing memory +fragmentation issues. +Each line starts with the identification of the node and the name +of the zone which together identify a memory region. +This is then +followed by the count of available chunks of a certain order in +which these zones are split. +The size in bytes of a certain order is given by the formula: +.IP +.in +4n +.EX +(2\[ha]order)\ *\ PAGE_SIZE +.EE +.in +.IP +The binary buddy allocator algorithm inside the kernel will split +one chunk into two chunks of a smaller order (thus with half the +size) or combine two contiguous chunks into one larger chunk of +a higher order (thus with double the size) to satisfy allocation +requests and to counter memory fragmentation. +The order matches the column number, when starting to count at zero. +.IP +For example on an x86-64 system: +.RS -12 +.EX +Node 0, zone DMA 1 1 1 0 2 1 1 0 1 1 3 +Node 0, zone DMA32 65 47 4 81 52 28 13 10 5 1 404 +Node 0, zone Normal 216 55 189 101 84 38 37 27 5 3 587 +.EE +.RE +.IP +In this example, there is one node containing three zones and there +are 11 different chunk sizes. +If the page size is 4 kilobytes, then the first zone called +.I DMA +(on x86 the first 16 megabyte of memory) has 1 chunk of 4 kilobytes +(order 0) available and has 3 chunks of 4 megabytes (order 10) available. +.IP +If the memory is heavily fragmented, the counters for higher +order chunks will be zero and allocation of large contiguous areas +will fail. +.IP +Further information about the zones can be found in +.IR /proc/zoneinfo . +.TP +.I /proc/bus +Contains subdirectories for installed buses. +.TP +.I /proc/bus/pccard +Subdirectory for PCMCIA devices when +.B CONFIG_PCMCIA +is set at kernel compilation time. +.TP +.I /proc/bus/pccard/drivers +.TP +.I /proc/bus/pci +Contains various bus subdirectories and pseudo-files containing +information about PCI buses, installed devices, and device +drivers. +Some of these files are not ASCII. +.TP +.I /proc/bus/pci/devices +Information about PCI devices. +They may be accessed through +.BR lspci (8) +and +.BR setpci (8). +.TP +.IR /proc/cgroups " (since Linux 2.6.24)" +See +.BR cgroups (7). +.TP +.I /proc/cmdline +Arguments passed to the Linux kernel at boot time. +Often done via a boot manager such as +.BR lilo (8) +or +.BR grub (8). +Any arguments embedded in the kernel image or initramfs via +.B CONFIG_BOOT_CONFIG +will also be displayed. +.TP +.IR /proc/config.gz " (since Linux 2.6)" +This file exposes the configuration options that were used +to build the currently running kernel, +in the same format as they would be shown in the +.I .config +file that resulted when configuring the kernel (using +.IR "make xconfig" , +.IR "make config" , +or similar). +The file contents are compressed; view or search them using +.BR zcat (1) +and +.BR zgrep (1). +As long as no changes have been made to the following file, +the contents of +.I /proc/config.gz +are the same as those provided by: +.IP +.in +4n +.EX +cat /lib/modules/$(uname \-r)/build/.config +.EE +.in +.IP +.I /proc/config.gz +is provided only if the kernel is configured with +.BR CONFIG_IKCONFIG_PROC . +.TP +.I /proc/crypto +A list of the ciphers provided by the kernel crypto API. +For details, see the kernel +.I "Linux Kernel Crypto API" +documentation available under the kernel source directory +.I Documentation/crypto/ +.\" commit 3b72c814a8e8cd638e1ba0da4dfce501e9dff5af +(or +.I Documentation/DocBook +before Linux 4.10; +the documentation can be built using a command such as +.I make htmldocs +in the root directory of the kernel source tree). +.TP +.I /proc/cpuinfo +This is a collection of CPU and system architecture dependent items, +for each supported architecture a different list. +Two common entries are \fIprocessor\fP which gives CPU number and +\fIbogomips\fP; a system constant that is calculated +during kernel initialization. +SMP machines have information for +each CPU. +The +.BR lscpu (1) +command gathers its information from this file. +.TP +.I /proc/devices +Text listing of major numbers and device groups. +This can be used by MAKEDEV scripts for consistency with the kernel. +.TP +.IR /proc/diskstats " (since Linux 2.5.69)" +This file contains disk I/O statistics for each disk device. +See the Linux kernel source file +.I Documentation/admin\-guide/iostats.rst +(or +.I Documentation/iostats.txt +before Linux 5.3) +for further information. +.TP +.I /proc/dma +This is a list of the registered \fIISA\fP DMA (direct memory access) +channels in use. +.TP +.I /proc/driver +Empty subdirectory. +.TP +.I /proc/execdomains +Used to list ABI personalities before Linux 4.1; +now contains a constant string for userspace compatibility. +.TP +.I /proc/fb +Frame buffer information when +.B CONFIG_FB +is defined during kernel compilation. +.TP +.I /proc/filesystems +A text listing of the filesystems which are supported by the kernel, +namely filesystems which were compiled into the kernel or whose kernel +modules are currently loaded. +(See also +.BR filesystems (5).) +If a filesystem is marked with "nodev", +this means that it does not require a block device to be mounted +(e.g., virtual filesystem, network filesystem). +.IP +Incidentally, this file may be used by +.BR mount (8) +when no filesystem is specified and it didn't manage to determine the +filesystem type. +Then filesystems contained in this file are tried +(excepted those that are marked with "nodev"). +.TP +.I /proc/fs +.\" FIXME Much more needs to be said about /proc/fs +.\" +Contains subdirectories that in turn contain files +with information about (certain) mounted filesystems. +.TP +.I /proc/ide +This directory +exists on systems with the IDE bus. +There are directories for each IDE channel and attached device. +Files include: +.IP +.in +4n +.EX +cache buffer size in KB +capacity number of sectors +driver driver version +geometry physical and logical geometry +identify in hexadecimal +media media type +model manufacturer\[aq]s model number +settings drive settings +smart_thresholds IDE disk management thresholds (in hex) +smart_values IDE disk management values (in hex) +.EE +.in +.IP +The +.BR hdparm (8) +utility provides access to this information in a friendly format. +.TP +.I /proc/interrupts +This is used to record the number of interrupts per CPU per IO device. +Since Linux 2.6.24, +for the i386 and x86-64 architectures, at least, this also includes +interrupts internal to the system (that is, not associated with a device +as such), such as NMI (nonmaskable interrupt), LOC (local timer interrupt), +and for SMP systems, TLB (TLB flush interrupt), RES (rescheduling +interrupt), CAL (remote function call interrupt), and possibly others. +Very easy to read formatting, done in ASCII. +.TP +.I /proc/iomem +I/O memory map in Linux 2.4. +.TP +.I /proc/ioports +This is a list of currently registered Input-Output port regions that +are in use. +.TP +.IR /proc/kallsyms " (since Linux 2.5.71)" +This holds the kernel exported symbol definitions used by the +.BR modules (X) +tools to dynamically link and bind loadable modules. +In Linux 2.5.47 and earlier, a similar file with slightly different syntax +was named +.IR ksyms . +.TP +.I /proc/kcore +This file represents the physical memory of the system and is stored +in the ELF core file format. +With this pseudo-file, and an unstripped +kernel +.RI ( /usr/src/linux/vmlinux ) +binary, GDB can be used to +examine the current state of any kernel data structures. +.IP +The total length of the file is the size of physical memory (RAM) plus +4\ KiB. +.TP +.IR /proc/keys " (since Linux 2.6.10)" +See +.BR keyrings (7). +.TP +.IR /proc/key\-users " (since Linux 2.6.10)" +See +.BR keyrings (7). +.TP +.I /proc/kmsg +This file can be used instead of the +.BR syslog (2) +system call to read kernel messages. +A process must have superuser +privileges to read this file, and only one process should read this +file. +This file should not be read if a syslog process is running +which uses the +.BR syslog (2) +system call facility to log kernel messages. +.IP +Information in this file is retrieved with the +.BR dmesg (1) +program. +.TP +.IR /proc/kpagecgroup " (since Linux 4.3)" +.\" commit 80ae2fdceba8313b0433f899bdd9c6c463291a17 +This file contains a 64-bit inode number of +the memory cgroup each page is charged to, +indexed by page frame number (see the discussion of +.IR /proc/ pid /pagemap ). +.IP +The +.I /proc/kpagecgroup +file is present only if the +.B CONFIG_MEMCG +kernel configuration option is enabled. +.TP +.IR /proc/kpagecount " (since Linux 2.6.25)" +This file contains a 64-bit count of the number of +times each physical page frame is mapped, +indexed by page frame number (see the discussion of +.IR /proc/ pid /pagemap ). +.IP +The +.I /proc/kpagecount +file is present only if the +.B CONFIG_PROC_PAGE_MONITOR +kernel configuration option is enabled. +.TP +.IR /proc/kpageflags " (since Linux 2.6.25)" +This file contains 64-bit masks corresponding to each physical page frame; +it is indexed by page frame number (see the discussion of +.IR /proc/ pid /pagemap ). +The bits are as follows: +.RS +.IP +.TS +r l l l. +0 - KPF_LOCKED +1 - KPF_ERROR +2 - KPF_REFERENCED +3 - KPF_UPTODATE +4 - KPF_DIRTY +5 - KPF_LRU +6 - KPF_ACTIVE +7 - KPF_SLAB +8 - KPF_WRITEBACK +9 - KPF_RECLAIM +10 - KPF_BUDDY +11 - KPF_MMAP (since Linux 2.6.31) +12 - KPF_ANON (since Linux 2.6.31) +13 - KPF_SWAPCACHE (since Linux 2.6.31) +14 - KPF_SWAPBACKED (since Linux 2.6.31) +15 - KPF_COMPOUND_HEAD (since Linux 2.6.31) +16 - KPF_COMPOUND_TAIL (since Linux 2.6.31) +17 - KPF_HUGE (since Linux 2.6.31) +18 - KPF_UNEVICTABLE (since Linux 2.6.31) +19 - KPF_HWPOISON (since Linux 2.6.31) +20 - KPF_NOPAGE (since Linux 2.6.31) +21 - KPF_KSM (since Linux 2.6.32) +22 - KPF_THP (since Linux 3.4) +23 - KPF_BALLOON (since Linux 3.18) +.\" KPF_BALLOON: commit 09316c09dde33aae14f34489d9e3d243ec0d5938 +24 - KPF_ZERO_PAGE (since Linux 4.0) +.\" KPF_ZERO_PAGE: commit 56873f43abdcd574b25105867a990f067747b2f4 +25 - KPF_IDLE (since Linux 4.3) +.\" KPF_IDLE: commit f074a8f49eb87cde95ac9d040ad5e7ea4f029738 +26 - KPF_PGTABLE (since Linux 4.18) +.\" KPF_PGTABLE: commit 1d40a5ea01d53251c23c7be541d3f4a656cfc537 +.TE +.RE +.IP +For further details on the meanings of these bits, +see the kernel source file +.IR Documentation/admin\-guide/mm/pagemap.rst . +Before Linux 2.6.29, +.\" commit ad3bdefe877afb47480418fdb05ecd42842de65e +.\" commit e07a4b9217d1e97d2f3a62b6b070efdc61212110 +.BR KPF_WRITEBACK , +.BR KPF_RECLAIM , +.BR KPF_BUDDY , +and +.B KPF_LOCKED +did not report correctly. +.IP +The +.I /proc/kpageflags +file is present only if the +.B CONFIG_PROC_PAGE_MONITOR +kernel configuration option is enabled. +.TP +.IR /proc/ksyms " (Linux 1.1.23\[en]2.5.47)" +See +.IR /proc/kallsyms . +.TP +.I /proc/loadavg +The first three fields in this file are load average figures +giving the number of jobs in the run queue (state R) +or waiting for disk I/O (state D) averaged over 1, 5, and 15 minutes. +They are the same as the load average numbers given by +.BR uptime (1) +and other programs. +The fourth field consists of two numbers separated by a slash (/). +The first of these is the number of currently runnable kernel +scheduling entities (processes, threads). +The value after the slash is the number of kernel scheduling entities +that currently exist on the system. +The fifth field is the PID of the process that was most +recently created on the system. +.TP +.I /proc/locks +This file shows current file locks +.RB ( flock "(2) and " fcntl (2)) +and leases +.RB ( fcntl (2)). +.IP +An example of the content shown in this file is the following: +.IP +.in +4n +.EX +1: POSIX ADVISORY READ 5433 08:01:7864448 128 128 +2: FLOCK ADVISORY WRITE 2001 08:01:7864554 0 EOF +3: FLOCK ADVISORY WRITE 1568 00:2f:32388 0 EOF +4: POSIX ADVISORY WRITE 699 00:16:28457 0 EOF +5: POSIX ADVISORY WRITE 764 00:16:21448 0 0 +6: POSIX ADVISORY READ 3548 08:01:7867240 1 1 +7: POSIX ADVISORY READ 3548 08:01:7865567 1826 2335 +8: OFDLCK ADVISORY WRITE \-1 08:01:8713209 128 191 +.EE +.in +.IP +The fields shown in each line are as follows: +.RS +.IP [1] 5 +The ordinal position of the lock in the list. +.IP [2] +The lock type. +Values that may appear here include: +.RS +.TP +.B FLOCK +This is a BSD file lock created using +.BR flock (2). +.TP +.B OFDLCK +This is an open file description (OFD) lock created using +.BR fcntl (2). +.TP +.B POSIX +This is a POSIX byte-range lock created using +.BR fcntl (2). +.RE +.IP [3] +Among the strings that can appear here are the following: +.RS +.TP +.B ADVISORY +This is an advisory lock. +.TP +.B MANDATORY +This is a mandatory lock. +.RE +.IP [4] +The type of lock. +Values that can appear here are: +.RS +.TP +.B READ +This is a POSIX or OFD read lock, or a BSD shared lock. +.TP +.B WRITE +This is a POSIX or OFD write lock, or a BSD exclusive lock. +.RE +.IP [5] +The PID of the process that owns the lock. +.IP +Because OFD locks are not owned by a single process +(since multiple processes may have file descriptors that +refer to the same open file description), +the value \-1 is displayed in this field for OFD locks. +(Before Linux 4.14, +.\" commit 9d5b86ac13c573795525ecac6ed2db39ab23e2a8 +a bug meant that the PID of the process that +initially acquired the lock was displayed instead of the value \-1.) +.IP [6] +Three colon-separated subfields that identify the major and minor device +ID of the device containing the filesystem where the locked file resides, +followed by the inode number of the locked file. +.IP [7] +The byte offset of the first byte of the lock. +For BSD locks, this value is always 0. +.IP [8] +The byte offset of the last byte of the lock. +.B EOF +in this field means that the lock extends to the end of the file. +For BSD locks, the value shown is always +.IR EOF . +.RE +.IP +Since Linux 4.9, +.\" commit d67fd44f697dff293d7cdc29af929241b669affe +the list of locks shown in +.I /proc/locks +is filtered to show just the locks for the processes in the PID +namespace (see +.BR pid_namespaces (7)) +for which the +.I /proc +filesystem was mounted. +(In the initial PID namespace, +there is no filtering of the records shown in this file.) +.IP +The +.BR lslocks (8) +command provides a bit more information about each lock. +.TP +.IR /proc/malloc " (only up to and including Linux 2.2)" +.\" It looks like this only ever did something back in 1.0 days +This file is present only if +.B CONFIG_DEBUG_MALLOC +was defined during compilation. +.TP +.I /proc/meminfo +This file reports statistics about memory usage on the system. +It is used by +.BR free (1) +to report the amount of free and used memory (both physical and swap) +on the system as well as the shared memory and buffers used by the +kernel. +Each line of the file consists of a parameter name, followed by a colon, +the value of the parameter, and an option unit of measurement (e.g., "kB"). +The list below describes the parameter names and +the format specifier required to read the field value. +Except as noted below, +all of the fields have been present since at least Linux 2.6.0. +Some fields are displayed only if the kernel was configured +with various options; those dependencies are noted in the list. +.RS +.TP +.IR MemTotal " %lu" +Total usable RAM (i.e., physical RAM minus a few reserved +bits and the kernel binary code). +.TP +.IR MemFree " %lu" +The sum of +.IR LowFree + HighFree . +.TP +.IR MemAvailable " %lu (since Linux 3.14)" +An estimate of how much memory is available for starting new +applications, without swapping. +.TP +.IR Buffers " %lu" +Relatively temporary storage for raw disk blocks that +shouldn't get tremendously large (20 MB or so). +.TP +.IR Cached " %lu" +In-memory cache for files read from the disk (the page cache). +Doesn't include +.IR SwapCached . +.TP +.IR SwapCached " %lu" +Memory that once was swapped out, is swapped back in but +still also is in the swap file. +(If memory pressure is high, these pages +don't need to be swapped out again because they are already +in the swap file. +This saves I/O.) +.TP +.IR Active " %lu" +Memory that has been used more recently and usually not +reclaimed unless absolutely necessary. +.TP +.IR Inactive " %lu" +Memory which has been less recently used. +It is more eligible to be reclaimed for other purposes. +.TP +.IR Active(anon) " %lu (since Linux 2.6.28)" +[To be documented.] +.TP +.IR Inactive(anon) " %lu (since Linux 2.6.28)" +[To be documented.] +.TP +.IR Active(file) " %lu (since Linux 2.6.28)" +[To be documented.] +.TP +.IR Inactive(file) " %lu (since Linux 2.6.28)" +[To be documented.] +.TP +.IR Unevictable " %lu (since Linux 2.6.28)" +(From Linux 2.6.28 to Linux 2.6.30, +\fBCONFIG_UNEVICTABLE_LRU\fP was required.) +[To be documented.] +.TP +.IR Mlocked " %lu (since Linux 2.6.28)" +(From Linux 2.6.28 to Linux 2.6.30, +\fBCONFIG_UNEVICTABLE_LRU\fP was required.) +[To be documented.] +.TP +.IR HighTotal " %lu" +(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.) +Total amount of highmem. +Highmem is all memory above \[ti]860 MB of physical memory. +Highmem areas are for use by user-space programs, +or for the page cache. +The kernel must use tricks to access +this memory, making it slower to access than lowmem. +.TP +.IR HighFree " %lu" +(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.) +Amount of free highmem. +.TP +.IR LowTotal " %lu" +(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.) +Total amount of lowmem. +Lowmem is memory which can be used for everything that +highmem can be used for, but it is also available for the +kernel's use for its own data structures. +Among many other things, +it is where everything from +.I Slab +is allocated. +Bad things happen when you're out of lowmem. +.TP +.IR LowFree " %lu" +(Starting with Linux 2.6.19, \fBCONFIG_HIGHMEM\fP is required.) +Amount of free lowmem. +.TP +.IR MmapCopy " %lu (since Linux 2.6.29)" +.RB ( CONFIG_MMU +is required.) +[To be documented.] +.TP +.IR SwapTotal " %lu" +Total amount of swap space available. +.TP +.IR SwapFree " %lu" +Amount of swap space that is currently unused. +.TP +.IR Dirty " %lu" +Memory which is waiting to get written back to the disk. +.TP +.IR Writeback " %lu" +Memory which is actively being written back to the disk. +.TP +.IR AnonPages " %lu (since Linux 2.6.18)" +Non-file backed pages mapped into user-space page tables. +.TP +.IR Mapped " %lu" +Files which have been mapped into memory (with +.BR mmap (2)), +such as libraries. +.TP +.IR Shmem " %lu (since Linux 2.6.32)" +Amount of memory consumed in +.BR tmpfs (5) +filesystems. +.TP +.IR KReclaimable " %lu (since Linux 4.20)" +Kernel allocations that the kernel will attempt to reclaim +under memory pressure. +Includes +.I SReclaimable +(below), and other direct allocations with a shrinker. +.TP +.IR Slab " %lu" +In-kernel data structures cache. +(See +.BR slabinfo (5).) +.TP +.IR SReclaimable " %lu (since Linux 2.6.19)" +Part of +.IR Slab , +that might be reclaimed, such as caches. +.TP +.IR SUnreclaim " %lu (since Linux 2.6.19)" +Part of +.IR Slab , +that cannot be reclaimed on memory pressure. +.TP +.IR KernelStack " %lu (since Linux 2.6.32)" +Amount of memory allocated to kernel stacks. +.TP +.IR PageTables " %lu (since Linux 2.6.18)" +Amount of memory dedicated to the lowest level of page tables. +.TP +.IR Quicklists " %lu (since Linux 2.6.27)" +(\fBCONFIG_QUICKLIST\fP is required.) +[To be documented.] +.TP +.IR NFS_Unstable " %lu (since Linux 2.6.18)" +NFS pages sent to the server, but not yet committed to stable storage. +.TP +.IR Bounce " %lu (since Linux 2.6.18)" +Memory used for block device "bounce buffers". +.TP +.IR WritebackTmp " %lu (since Linux 2.6.26)" +Memory used by FUSE for temporary writeback buffers. +.TP +.IR CommitLimit " %lu (since Linux 2.6.10)" +This is the total amount of memory currently available to +be allocated on the system, expressed in kilobytes. +This limit is adhered to +only if strict overcommit accounting is enabled (mode 2 in +.IR /proc/sys/vm/overcommit_memory ). +The limit is calculated according to the formula described under +.IR /proc/sys/vm/overcommit_memory . +For further details, see the kernel source file +.IR Documentation/vm/overcommit\-accounting.rst . +.TP +.IR Committed_AS " %lu" +The amount of memory presently allocated on the system. +The committed memory is a sum of all of the memory which +has been allocated by processes, even if it has not been +"used" by them as of yet. +A process which allocates 1 GB of memory (using +.BR malloc (3) +or similar), but touches only 300 MB of that memory will show up +as using only 300 MB of memory even if it has the address space +allocated for the entire 1 GB. +.IP +This 1 GB is memory which has been "committed" to by the VM +and can be used at any time by the allocating application. +With strict overcommit enabled on the system (mode 2 in +.IR /proc/sys/vm/overcommit_memory ), +allocations which would exceed the +.I CommitLimit +will not be permitted. +This is useful if one needs to guarantee that processes will not +fail due to lack of memory once that memory has been successfully allocated. +.TP +.IR VmallocTotal " %lu" +Total size of vmalloc memory area. +.TP +.IR VmallocUsed " %lu" +Amount of vmalloc area which is used. +Since Linux 4.4, +.\" commit a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0 +this field is no longer calculated, and is hard coded as 0. +See +.IR /proc/vmallocinfo . +.TP +.IR VmallocChunk " %lu" +Largest contiguous block of vmalloc area which is free. +Since Linux 4.4, +.\" commit a5ad88ce8c7fae7ddc72ee49a11a75aa837788e0 +this field is no longer calculated and is hard coded as 0. +See +.IR /proc/vmallocinfo . +.TP +.IR HardwareCorrupted " %lu (since Linux 2.6.32)" +(\fBCONFIG_MEMORY_FAILURE\fP is required.) +[To be documented.] +.TP +.IR LazyFree " %lu (since Linux 4.12)" +Shows the amount of memory marked by +.BR madvise (2) +.BR MADV_FREE . +.TP +.IR AnonHugePages " %lu (since Linux 2.6.38)" +(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.) +Non-file backed huge pages mapped into user-space page tables. +.TP +.IR ShmemHugePages " %lu (since Linux 4.8)" +(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.) +Memory used by shared memory (shmem) and +.BR tmpfs (5) +allocated with huge pages. +.TP +.IR ShmemPmdMapped " %lu (since Linux 4.8)" +(\fBCONFIG_TRANSPARENT_HUGEPAGE\fP is required.) +Shared memory mapped into user space with huge pages. +.TP +.IR CmaTotal " %lu (since Linux 3.1)" +Total CMA (Contiguous Memory Allocator) pages. +(\fBCONFIG_CMA\fP is required.) +.TP +.IR CmaFree " %lu (since Linux 3.1)" +Free CMA (Contiguous Memory Allocator) pages. +(\fBCONFIG_CMA\fP is required.) +.TP +.IR HugePages_Total " %lu" +(\fBCONFIG_HUGETLB_PAGE\fP is required.) +The size of the pool of huge pages. +.TP +.IR HugePages_Free " %lu" +(\fBCONFIG_HUGETLB_PAGE\fP is required.) +The number of huge pages in the pool that are not yet allocated. +.TP +.IR HugePages_Rsvd " %lu (since Linux 2.6.17)" +(\fBCONFIG_HUGETLB_PAGE\fP is required.) +This is the number of huge pages for +which a commitment to allocate from the pool has been made, +but no allocation has yet been made. +These reserved huge pages +guarantee that an application will be able to allocate a +huge page from the pool of huge pages at fault time. +.TP +.IR HugePages_Surp " %lu (since Linux 2.6.24)" +(\fBCONFIG_HUGETLB_PAGE\fP is required.) +This is the number of huge pages in +the pool above the value in +.IR /proc/sys/vm/nr_hugepages . +The maximum number of surplus huge pages is controlled by +.IR /proc/sys/vm/nr_overcommit_hugepages . +.TP +.IR Hugepagesize " %lu" +(\fBCONFIG_HUGETLB_PAGE\fP is required.) +The size of huge pages. +.TP +.IR DirectMap4k " %lu (since Linux 2.6.27)" +Number of bytes of RAM linearly mapped by kernel in 4 kB pages. +(x86.) +.TP +.IR DirectMap4M " %lu (since Linux 2.6.27)" +Number of bytes of RAM linearly mapped by kernel in 4 MB pages. +(x86 with +.B CONFIG_X86_64 +or +.B CONFIG_X86_PAE +enabled.) +.TP +.IR DirectMap2M " %lu (since Linux 2.6.27)" +Number of bytes of RAM linearly mapped by kernel in 2 MB pages. +(x86 with neither +.B CONFIG_X86_64 +nor +.B CONFIG_X86_PAE +enabled.) +.TP +.IR DirectMap1G " %lu (since Linux 2.6.27)" +(x86 with +.B CONFIG_X86_64 +and +.B CONFIG_X86_DIRECT_GBPAGES +enabled.) +.RE +.TP +.I /proc/modules +A text list of the modules that have been loaded by the system. +See also +.BR lsmod (8). +.TP +.I /proc/mounts +Before Linux 2.4.19, this file was a list +of all the filesystems currently mounted on the system. +With the introduction of per-process mount namespaces in Linux 2.4.19 (see +.BR mount_namespaces (7)), +this file became a link to +.IR /proc/self/mounts , +which lists the mounts of the process's own mount namespace. +The format of this file is documented in +.BR fstab (5). +.TP +.I /proc/mtrr +Memory Type Range Registers. +See the Linux kernel source file +.I Documentation/x86/mtrr.rst +(or +.I Documentation/x86/mtrr.txt +.\" commit 7225e75144b9718cbbe1820d9c011c809d5773fd +before Linux 5.2, or +.I Documentation/mtrr.txt +before Linux 2.6.28) +for details. +.TP +.I /proc/net +This directory contains various files and subdirectories containing +information about the networking layer. +The files contain ASCII structures and are, +therefore, readable with +.BR cat (1). +However, the standard +.BR netstat (8) +suite provides much cleaner access to these files. +.IP +With the advent of network namespaces, +various information relating to the network stack is virtualized (see +.BR network_namespaces (7)). +Thus, since Linux 2.6.25, +.\" commit e9720acd728a46cb40daa52c99a979f7c4ff195c +.I /proc/net +is a symbolic link to the directory +.IR /proc/self/net , +which contains the same files and directories as listed below. +However, these files and directories now expose information +for the network namespace of which the process is a member. +.TP +.I /proc/net/arp +This holds an ASCII readable dump of the kernel ARP table used for +address resolutions. +It will show both dynamically learned and preprogrammed ARP entries. +The format is: +.IP +.in +4n +.EX +IP address HW type Flags HW address Mask Device +192.168.0.50 0x1 0x2 00:50:BF:25:68:F3 * eth0 +192.168.0.250 0x1 0xc 00:00:00:00:00:00 * eth0 +.EE +.in +.IP +Here "IP address" is the IPv4 address of the machine and the "HW type" +is the hardware type of the address from RFC\ 826. +The flags are the internal +flags of the ARP structure (as defined in +.IR /usr/include/linux/if_arp.h ) +and +the "HW address" is the data link layer mapping for that IP address if +it is known. +.TP +.I /proc/net/dev +The dev pseudo-file contains network device status information. +This gives +the number of received and sent packets, the number of errors and +collisions +and other basic statistics. +These are used by the +.BR ifconfig (8) +program to report device status. +The format is: +.IP +.EX +Inter\-| Receive | Transmit + face |bytes packets errs drop fifo frame compressed multicast|bytes packets errs drop fifo colls carrier compressed + lo: 2776770 11307 0 0 0 0 0 0 2776770 11307 0 0 0 0 0 0 + eth0: 1215645 2751 0 0 0 0 0 0 1782404 4324 0 0 0 427 0 0 + ppp0: 1622270 5552 1 0 0 0 0 0 354130 5669 0 0 0 0 0 0 + tap0: 7714 81 0 0 0 0 0 0 7714 81 0 0 0 0 0 0 +.EE +.\" .TP +.\" .I /proc/net/ipx +.\" No information. +.\" .TP +.\" .I /proc/net/ipx_route +.\" No information. +.TP +.I /proc/net/dev_mcast +Defined in +.IR /usr/src/linux/net/core/dev_mcast.c : +.IP +.in +4n +.EX +indx interface_name dmi_u dmi_g dmi_address +2 eth0 1 0 01005e000001 +3 eth1 1 0 01005e000001 +4 eth2 1 0 01005e000001 +.EE +.in +.TP +.I /proc/net/igmp +Internet Group Management Protocol. +Defined in +.IR /usr/src/linux/net/core/igmp.c . +.TP +.I /proc/net/rarp +This file uses the same format as the +.I arp +file and contains the current reverse mapping database used to provide +.BR rarp (8) +reverse address lookup services. +If RARP is not configured into the +kernel, +this file will not be present. +.TP +.I /proc/net/raw +Holds a dump of the RAW socket table. +Much of the information is not of +use +apart from debugging. +The "sl" value is the kernel hash slot for the +socket, +the "local_address" is the local address and protocol number pair. +\&"St" is +the internal status of the socket. +The "tx_queue" and "rx_queue" are the +outgoing and incoming data queue in terms of kernel memory usage. +The "tr", "tm\->when", and "rexmits" fields are not used by RAW. +The "uid" +field holds the effective UID of the creator of the socket. +.\" .TP +.\" .I /proc/net/route +.\" No information, but looks similar to +.\" .BR route (8). +.TP +.I /proc/net/snmp +This file holds the ASCII data needed for the IP, ICMP, TCP, and UDP +management +information bases for an SNMP agent. +.TP +.I /proc/net/tcp +Holds a dump of the TCP socket table. +Much of the information is not +of use apart from debugging. +The "sl" value is the kernel hash slot +for the socket, the "local_address" is the local address and port number pair. +The "rem_address" is the remote address and port number pair +(if connected). +\&"St" is the internal status of the socket. +The "tx_queue" and "rx_queue" are the +outgoing and incoming data queue in terms of kernel memory usage. +The "tr", "tm\->when", and "rexmits" fields hold internal information of +the kernel socket state and are useful only for debugging. +The "uid" +field holds the effective UID of the creator of the socket. +.TP +.I /proc/net/udp +Holds a dump of the UDP socket table. +Much of the information is not of +use apart from debugging. +The "sl" value is the kernel hash slot for the +socket, the "local_address" is the local address and port number pair. +The "rem_address" is the remote address and port number pair +(if connected). +"St" is the internal status of the socket. +The "tx_queue" and "rx_queue" are the outgoing and incoming data queue +in terms of kernel memory usage. +The "tr", "tm\->when", and "rexmits" fields +are not used by UDP. +The "uid" +field holds the effective UID of the creator of the socket. +The format is: +.IP +.EX +sl local_address rem_address st tx_queue rx_queue tr rexmits tm\->when uid + 1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0 + 1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0 + 1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 +.EE +.TP +.I /proc/net/unix +Lists the UNIX domain sockets present within the system and their +status. +The format is: +.IP +.EX +Num RefCount Protocol Flags Type St Inode Path + 0: 00000002 00000000 00000000 0001 03 42 + 1: 00000001 00000000 00010000 0001 01 1948 /dev/printer +.EE +.IP +The fields are as follows: +.RS +.TP 10 +.IR Num : +the kernel table slot number. +.TP +.IR RefCount : +the number of users of the socket. +.TP +.IR Protocol : +currently always 0. +.TP +.IR Flags : +the internal kernel flags holding the status of the socket. +.TP +.IR Type : +the socket type. +For +.B SOCK_STREAM +sockets, this is 0001; for +.B SOCK_DGRAM +sockets, it is 0002; and for +.B SOCK_SEQPACKET +sockets, it is 0005. +.TP +.IR St : +the internal state of the socket. +.TP +.IR Inode : +the inode number of the socket. +.TP +.IR Path : +the bound pathname (if any) of the socket. +Sockets in the abstract namespace are included in the list, +and are shown with a +.I Path +that commences with the character '@'. +.RE +.TP +.I /proc/net/netfilter/nfnetlink_queue +This file contains information about netfilter user-space queueing, if used. +Each line represents a queue. +Queues that have not been subscribed to +by user space are not shown. +.IP +.in +4n +.EX + 1 4207 0 2 65535 0 0 0 1 + (1) (2) (3)(4) (5) (6) (7) (8) +.EE +.in +.IP +The fields in each line are: +.RS 7 +.TP 5 +(1) +The ID of the queue. +This matches what is specified in the +.B \-\-queue\-num +or +.B \-\-queue\-balance +options to the +.BR iptables (8) +NFQUEUE target. +See +.BR iptables\-extensions (8) +for more information. +.TP +(2) +The netlink port ID subscribed to the queue. +.TP +(3) +The number of packets currently queued and waiting to be processed by +the application. +.TP +(4) +The copy mode of the queue. +It is either 1 (metadata only) or 2 +(also copy payload data to user space). +.TP +(5) +Copy range; that is, how many bytes of packet payload should be copied to +user space at most. +.TP +(6) +queue dropped. +Number of packets that had to be dropped by the kernel because +too many packets are already waiting for user space to send back the mandatory +accept/drop verdicts. +.TP +(7) +queue user dropped. +Number of packets that were dropped within the netlink +subsystem. +Such drops usually happen when the corresponding socket buffer is +full; that is, user space is not able to read messages fast enough. +.TP +(8) +sequence number. +Every queued packet is associated with a (32-bit) +monotonically increasing sequence number. +This shows the ID of the most recent packet queued. +.RE +.IP +The last number exists only for compatibility reasons and is always 1. +.TP +.I /proc/partitions +Contains the major and minor numbers of each partition as well as the number +of 1024-byte blocks and the partition name. +.TP +.I /proc/pci +This is a listing of all PCI devices found during kernel initialization +and their configuration. +.IP +This file has been deprecated in favor of a new +.I /proc +interface for PCI +.RI ( /proc/bus/pci ). +It became optional in Linux 2.2 (available with +.B CONFIG_PCI_OLD_PROC +set at kernel compilation). +It became once more nonoptionally enabled in Linux 2.4. +Next, it was deprecated in Linux 2.6 (still available with +.B CONFIG_PCI_LEGACY_PROC +set), and finally removed altogether since Linux 2.6.17. +.\" FIXME Document /proc/sched_debug (since Linux 2.6.23) +.\" See also /proc/[pid]/sched +.TP +.IR /proc/profile " (since Linux 2.4)" +This file is present only if the kernel was booted with the +.I profile=1 +command-line option. +It exposes kernel profiling information in a binary format for use by +.BR readprofile (1). +Writing (e.g., an empty string) to this file resets the profiling counters; +on some architectures, +writing a binary integer "profiling multiplier" of size +.I sizeof(int) +sets the profiling interrupt frequency. +.TP +.I /proc/scsi +A directory with the +.I scsi +mid-level pseudo-file and various SCSI low-level +driver directories, +which contain a file for each SCSI host in this system, all of +which give the status of some part of the SCSI IO subsystem. +These files contain ASCII structures and are, therefore, readable with +.BR cat (1). +.IP +You can also write to some of the files to reconfigure the subsystem or +switch certain features on or off. +.TP +.I /proc/scsi/scsi +This is a listing of all SCSI devices known to the kernel. +The listing is similar to the one seen during bootup. +scsi currently supports only the \fIadd\-single\-device\fP command which +allows root to add a hotplugged device to the list of known devices. +.IP +The command +.IP +.in +4n +.EX +echo \[aq]scsi add\-single\-device 1 0 5 0\[aq] > /proc/scsi/scsi +.EE +.in +.IP +will cause +host scsi1 to scan on SCSI channel 0 for a device on ID 5 LUN 0. +If there +is already a device known on this address or the address is invalid, an +error will be returned. +.TP +.IR /proc/scsi/ drivername +\fIdrivername\fP can currently be NCR53c7xx, aha152x, aha1542, aha1740, +aic7xxx, buslogic, eata_dma, eata_pio, fdomain, in2000, pas16, qlogic, +scsi_debug, seagate, t128, u15\-24f, ultrastore, or wd7000. +These directories show up for all drivers that registered at least one +SCSI HBA. +Every directory contains one file per registered host. +Every host-file is named after the number the host was assigned during +initialization. +.IP +Reading these files will usually show driver and host configuration, +statistics, and so on. +.IP +Writing to these files allows different things on different hosts. +For example, with the \fIlatency\fP and \fInolatency\fP commands, +root can switch on and off command latency measurement code in the +eata_dma driver. +With the \fIlockup\fP and \fIunlock\fP commands, +root can control bus lockups simulated by the scsi_debug driver. +.TP +.I /proc/self +This directory refers to the process accessing the +.I /proc +filesystem, +and is identical to the +.I /proc +directory named by the process ID of the same process. +.TP +.I /proc/slabinfo +Information about kernel caches. +See +.BR slabinfo (5) +for details. +.TP +.I /proc/stat +kernel/system statistics. +Varies with architecture. +Common +entries include: +.RS +.TP +.I cpu 10132153 290696 3084719 46828483 16683 0 25195 0 175628 0 +.TQ +.I cpu0 1393280 32966 572056 13343292 6130 0 17875 0 23933 0 +The amount of time, measured in units of +USER_HZ (1/100ths of a second on most architectures, use +.I sysconf(_SC_CLK_TCK) +to obtain the right value), +.\" 1024 on Alpha and ia64 +that the system ("cpu" line) or the specific CPU ("cpu\fIN\fR" line) +spent in various states: +.RS +.TP +.I user +(1) Time spent in user mode. +.TP +.I nice +(2) Time spent in user mode with low priority (nice). +.TP +.I system +(3) Time spent in system mode. +.TP +.I idle +(4) Time spent in the idle task. +.\" FIXME . Actually, the following info about the /proc/stat 'cpu' field +.\" does not seem to be quite right (at least in Linux 2.6.12 or Linux 3.6): +.\" the idle time in /proc/uptime does not quite match this value +This value should be USER_HZ times the +second entry in the +.I /proc/uptime +pseudo-file. +.TP +.IR iowait " (since Linux 2.5.41)" +(5) Time waiting for I/O to complete. +This value is not reliable, for the following reasons: +.\" See kernel commit 9c240d757658a3ae9968dd309e674c61f07c7f48 +.RS +.IP \[bu] 3 +The CPU will not wait for I/O to complete; +iowait is the time that a task is waiting for I/O to complete. +When a CPU goes into idle state for outstanding task I/O, +another task will be scheduled on this CPU. +.IP \[bu] +On a multi-core CPU, +the task waiting for I/O to complete is not running on any CPU, +so the iowait of each CPU is difficult to calculate. +.IP \[bu] +The value in this field may +.I decrease +in certain conditions. +.RE +.TP +.IR irq " (since Linux 2.6.0)" +.\" Precisely: Linux 2.6.0-test4 +(6) Time servicing interrupts. +.TP +.IR softirq " (since Linux 2.6.0)" +.\" Precisely: Linux 2.6.0-test4 +(7) Time servicing softirqs. +.TP +.IR steal " (since Linux 2.6.11)" +(8) Stolen time, which is the time spent in other operating systems when +running in a virtualized environment +.TP +.IR guest " (since Linux 2.6.24)" +(9) Time spent running a virtual CPU for guest +operating systems under the control of the Linux kernel. +.\" See Changelog entry for 5e84cfde51cf303d368fcb48f22059f37b3872de +.TP +.IR guest_nice " (since Linux 2.6.33)" +.\" commit ce0e7b28fb75cb003cfc8d0238613aaf1c55e797 +(10) Time spent running a niced guest (virtual CPU for guest +operating systems under the control of the Linux kernel). +.RE +.TP +\fIpage 5741 1808\fP +The number of pages the system paged in and the number that were paged +out (from disk). +.TP +\fIswap 1 0\fP +The number of swap pages that have been brought in and out. +.TP +.\" FIXME . The following is not the full picture for the 'intr' of +.\" /proc/stat on 2.6: +\fIintr 1462898\fP +This line shows counts of interrupts serviced since boot time, +for each of the possible system interrupts. +The first column is the total of all interrupts serviced +including unnumbered architecture specific interrupts; +each subsequent column is the total for that particular numbered interrupt. +Unnumbered interrupts are not shown, only summed into the total. +.TP +\fIdisk_io: (2,0):(31,30,5764,1,2) (3,0):\fP... +(major,disk_idx):(noinfo, read_io_ops, blks_read, write_io_ops, blks_written) +.br +(Linux 2.4 only) +.TP +\fIctxt 115315\fP +The number of context switches that the system underwent. +.TP +\fIbtime 769041601\fP +boot time, in seconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC). +.TP +\fIprocesses 86031\fP +Number of forks since boot. +.TP +\fIprocs_running 6\fP +Number of processes in runnable state. +(Linux 2.5.45 onward.) +.TP +\fIprocs_blocked 2\fP +Number of processes blocked waiting for I/O to complete. +(Linux 2.5.45 onward.) +.TP +.I softirq 229245889 94 60001584 13619 5175704 2471304 28 51212741 59130143 0 51240672 +.\" commit d3d64df21d3d0de675a0d3ffa7c10514f3644b30 +This line shows the number of softirq for all CPUs. +The first column is the total of all softirqs and +each subsequent column is the total for particular softirq. +(Linux 2.6.31 onward.) +.RE +.TP +.I /proc/swaps +Swap areas in use. +See also +.BR swapon (8). +.TP +.I /proc/sys +This directory (present since Linux 1.3.57) contains a number of files +and subdirectories corresponding to kernel variables. +These variables can be read and in some cases modified using +the \fI/proc\fP filesystem, and the (deprecated) +.BR sysctl (2) +system call. +.IP +String values may be terminated by either \[aq]\e0\[aq] or \[aq]\en\[aq]. +.IP +Integer and long values may be written either in decimal or in +hexadecimal notation (e.g., 0x3FFF). +When writing multiple integer or long values, these may be separated +by any of the following whitespace characters: +\[aq]\ \[aq], \[aq]\et\[aq], or \[aq]\en\[aq]. +Using other separators leads to the error +.BR EINVAL . +.TP +.IR /proc/sys/abi " (since Linux 2.4.10)" +This directory may contain files with application binary information. +.\" On some systems, it is not present. +See the Linux kernel source file +.I Documentation/sysctl/abi.rst +(or +.I Documentation/sysctl/abi.txt +before Linux 5.3) +for more information. +.TP +.I /proc/sys/debug +This directory may be empty. +.TP +.I /proc/sys/dev +This directory contains device-specific information (e.g., +.IR dev/cdrom/info ). +On +some systems, it may be empty. +.TP +.I /proc/sys/fs +This directory contains the files and subdirectories for kernel variables +related to filesystems. +.TP +.IR /proc/sys/fs/aio\-max\-nr " and " /proc/sys/fs/aio\-nr " (since Linux 2.6.4)" +.I aio\-nr +is the running total of the number of events specified by +.BR io_setup (2) +calls for all currently active AIO contexts. +If +.I aio\-nr +reaches +.IR aio\-max\-nr , +then +.BR io_setup (2) +will fail with the error +.BR EAGAIN . +Raising +.I aio\-max\-nr +does not result in the preallocation or resizing +of any kernel data structures. +.TP +.I /proc/sys/fs/binfmt_misc +Documentation for files in this directory can be found +in the Linux kernel source in the file +.I Documentation/admin\-guide/binfmt\-misc.rst +(or in +.I Documentation/binfmt_misc.txt +on older kernels). +.TP +.IR /proc/sys/fs/dentry\-state " (since Linux 2.2)" +This file contains information about the status of the +directory cache (dcache). +The file contains six numbers, +.IR nr_dentry , +.IR nr_unused , +.I age_limit +(age in seconds), +.I want_pages +(pages requested by system) and two dummy values. +.RS +.IP \[bu] 3 +.I nr_dentry +is the number of allocated dentries (dcache entries). +This field is unused in Linux 2.2. +.IP \[bu] +.I nr_unused +is the number of unused dentries. +.IP \[bu] +.I age_limit +.\" looks like this is unused in Linux 2.2 to Linux 2.6 +is the age in seconds after which dcache entries +can be reclaimed when memory is short. +.IP \[bu] +.I want_pages +.\" looks like this is unused in Linux 2.2 to Linux 2.6 +is nonzero when the kernel has called shrink_dcache_pages() and the +dcache isn't pruned yet. +.RE +.TP +.I /proc/sys/fs/dir\-notify\-enable +This file can be used to disable or enable the +.I dnotify +interface described in +.BR fcntl (2) +on a system-wide basis. +A value of 0 in this file disables the interface, +and a value of 1 enables it. +.TP +.I /proc/sys/fs/dquot\-max +This file shows the maximum number of cached disk quota entries. +On some (2.4) systems, it is not present. +If the number of free cached disk quota entries is very low and +you have some awesome number of simultaneous system users, +you might want to raise the limit. +.TP +.I /proc/sys/fs/dquot\-nr +This file shows the number of allocated disk quota +entries and the number of free disk quota entries. +.TP +.IR /proc/sys/fs/epoll " (since Linux 2.6.28)" +This directory contains the file +.IR max_user_watches , +which can be used to limit the amount of kernel memory consumed by the +.I epoll +interface. +For further details, see +.BR epoll (7). +.TP +.I /proc/sys/fs/file\-max +This file defines +a system-wide limit on the number of open files for all processes. +System calls that fail when encountering this limit fail with the error +.BR ENFILE . +(See also +.BR setrlimit (2), +which can be used by a process to set the per-process limit, +.BR RLIMIT_NOFILE , +on the number of files it may open.) +If you get lots +of error messages in the kernel log about running out of file handles +(open file descriptions) +(look for "VFS: file\-max limit <number> reached"), +try increasing this value: +.IP +.in +4n +.EX +echo 100000 > /proc/sys/fs/file\-max +.EE +.in +.IP +Privileged processes +.RB ( CAP_SYS_ADMIN ) +can override the +.I file\-max +limit. +.TP +.I /proc/sys/fs/file\-nr +This (read-only) file contains three numbers: +the number of allocated file handles +(i.e., the number of open file descriptions; see +.BR open (2)); +the number of free file handles; +and the maximum number of file handles (i.e., the same value as +.IR /proc/sys/fs/file\-max ). +If the number of allocated file handles is close to the +maximum, you should consider increasing the maximum. +Before Linux 2.6, +the kernel allocated file handles dynamically, +but it didn't free them again. +Instead the free file handles were kept in a list for reallocation; +the "free file handles" value indicates the size of that list. +A large number of free file handles indicates that there was +a past peak in the usage of open file handles. +Since Linux 2.6, the kernel does deallocate freed file handles, +and the "free file handles" value is always zero. +.TP +.IR /proc/sys/fs/inode\-max " (only present until Linux 2.2)" +This file contains the maximum number of in-memory inodes. +This value should be 3\[en]4 times larger +than the value in +.IR file\-max , +since \fIstdin\fP, \fIstdout\fP +and network sockets also need an inode to handle them. +When you regularly run out of inodes, you need to increase this value. +.IP +Starting with Linux 2.4, +there is no longer a static limit on the number of inodes, +and this file is removed. +.TP +.I /proc/sys/fs/inode\-nr +This file contains the first two values from +.IR inode\-state . +.TP +.I /proc/sys/fs/inode\-state +This file +contains seven numbers: +.IR nr_inodes , +.IR nr_free_inodes , +.IR preshrink , +and four dummy values (always zero). +.IP +.I nr_inodes +is the number of inodes the system has allocated. +.\" This can be slightly more than +.\" .I inode\-max +.\" because Linux allocates them one page full at a time. +.I nr_free_inodes +represents the number of free inodes. +.IP +.I preshrink +is nonzero when the +.I nr_inodes +> +.I inode\-max +and the system needs to prune the inode list instead of allocating more; +since Linux 2.4, this field is a dummy value (always zero). +.TP +.IR /proc/sys/fs/inotify " (since Linux 2.6.13)" +This directory contains files +.IR max_queued_events ", " max_user_instances ", and " max_user_watches , +that can be used to limit the amount of kernel memory consumed by the +.I inotify +interface. +For further details, see +.BR inotify (7). +.TP +.I /proc/sys/fs/lease\-break\-time +This file specifies the grace period that the kernel grants to a process +holding a file lease +.RB ( fcntl (2)) +after it has sent a signal to that process notifying it +that another process is waiting to open the file. +If the lease holder does not remove or downgrade the lease within +this grace period, the kernel forcibly breaks the lease. +.TP +.I /proc/sys/fs/leases\-enable +This file can be used to enable or disable file leases +.RB ( fcntl (2)) +on a system-wide basis. +If this file contains the value 0, leases are disabled. +A nonzero value enables leases. +.TP +.IR /proc/sys/fs/mount\-max " (since Linux 4.9)" +.\" commit d29216842a85c7970c536108e093963f02714498 +The value in this file specifies the maximum number of mounts that may exist +in a mount namespace. +The default value in this file is 100,000. +.TP +.IR /proc/sys/fs/mqueue " (since Linux 2.6.6)" +This directory contains files +.IR msg_max ", " msgsize_max ", and " queues_max , +controlling the resources used by POSIX message queues. +See +.BR mq_overview (7) +for details. +.TP +.IR /proc/sys/fs/nr_open " (since Linux 2.6.25)" +.\" commit 9cfe015aa424b3c003baba3841a60dd9b5ad319b +This file imposes a ceiling on the value to which the +.B RLIMIT_NOFILE +resource limit can be raised (see +.BR getrlimit (2)). +This ceiling is enforced for both unprivileged and privileged process. +The default value in this file is 1048576. +(Before Linux 2.6.25, the ceiling for +.B RLIMIT_NOFILE +was hard-coded to the same value.) +.TP +.IR /proc/sys/fs/overflowgid " and " /proc/sys/fs/overflowuid +These files +allow you to change the value of the fixed UID and GID. +The default is 65534. +Some filesystems support only 16-bit UIDs and GIDs, although in Linux +UIDs and GIDs are 32 bits. +When one of these filesystems is mounted +with writes enabled, any UID or GID that would exceed 65535 is translated +to the overflow value before being written to disk. +.TP +.IR /proc/sys/fs/pipe\-max\-size " (since Linux 2.6.35)" +See +.BR pipe (7). +.TP +.IR /proc/sys/fs/pipe\-user\-pages\-hard " (since Linux 4.5)" +See +.BR pipe (7). +.TP +.IR /proc/sys/fs/pipe\-user\-pages\-soft " (since Linux 4.5)" +See +.BR pipe (7). +.TP +.IR /proc/sys/fs/protected_fifos " (since Linux 4.19)" +The value in this file is/can be set to one of the following: +.RS +.TP 4 +0 +Writing to FIFOs is unrestricted. +.TP +1 +Don't allow +.B O_CREAT +.BR open (2) +on FIFOs that the caller doesn't own in world-writable sticky directories, +unless the FIFO is owned by the owner of the directory. +.TP +2 +As for the value 1, +but the restriction also applies to group-writable sticky directories. +.RE +.IP +The intent of the above protections is to avoid unintentional writes to an +attacker-controlled FIFO when a program expected to create a regular file. +.TP +.IR /proc/sys/fs/protected_hardlinks " (since Linux 3.6)" +.\" commit 800179c9b8a1e796e441674776d11cd4c05d61d7 +When the value in this file is 0, +no restrictions are placed on the creation of hard links +(i.e., this is the historical behavior before Linux 3.6). +When the value in this file is 1, +a hard link can be created to a target file +only if one of the following conditions is true: +.RS +.IP \[bu] 3 +The calling process has the +.B CAP_FOWNER +capability in its user namespace +and the file UID has a mapping in the namespace. +.IP \[bu] +The filesystem UID of the process creating the link matches +the owner (UID) of the target file +(as described in +.BR credentials (7), +a process's filesystem UID is normally the same as its effective UID). +.IP \[bu] +All of the following conditions are true: +.RS 4 +.IP \[bu] 3 +the target is a regular file; +.IP \[bu] +the target file does not have its set-user-ID mode bit enabled; +.IP \[bu] +the target file does not have both its set-group-ID and +group-executable mode bits enabled; and +.IP \[bu] +the caller has permission to read and write the target file +(either via the file's permissions mask or because it has +suitable capabilities). +.RE +.RE +.IP +The default value in this file is 0. +Setting the value to 1 +prevents a longstanding class of security issues caused by +hard-link-based time-of-check, time-of-use races, +most commonly seen in world-writable directories such as +.IR /tmp . +The common method of exploiting this flaw +is to cross privilege boundaries when following a given hard link +(i.e., a root process follows a hard link created by another user). +Additionally, on systems without separated partitions, +this stops unauthorized users from "pinning" vulnerable set-user-ID and +set-group-ID files against being upgraded by +the administrator, or linking to special files. +.TP +.IR /proc/sys/fs/protected_regular " (since Linux 4.19)" +The value in this file is/can be set to one of the following: +.RS +.TP 4 +0 +Writing to regular files is unrestricted. +.TP +1 +Don't allow +.B O_CREAT +.BR open (2) +on regular files that the caller doesn't own in +world-writable sticky directories, +unless the regular file is owned by the owner of the directory. +.TP +2 +As for the value 1, +but the restriction also applies to group-writable sticky directories. +.RE +.IP +The intent of the above protections is similar to +.IR protected_fifos , +but allows an application to +avoid writes to an attacker-controlled regular file, +where the application expected to create one. +.TP +.IR /proc/sys/fs/protected_symlinks " (since Linux 3.6)" +.\" commit 800179c9b8a1e796e441674776d11cd4c05d61d7 +When the value in this file is 0, +no restrictions are placed on following symbolic links +(i.e., this is the historical behavior before Linux 3.6). +When the value in this file is 1, symbolic links are followed only +in the following circumstances: +.RS +.IP \[bu] 3 +the filesystem UID of the process following the link matches +the owner (UID) of the symbolic link +(as described in +.BR credentials (7), +a process's filesystem UID is normally the same as its effective UID); +.IP \[bu] +the link is not in a sticky world-writable directory; or +.IP \[bu] +the symbolic link and its parent directory have the same owner (UID) +.RE +.IP +A system call that fails to follow a symbolic link +because of the above restrictions returns the error +.B EACCES +in +.IR errno . +.IP +The default value in this file is 0. +Setting the value to 1 avoids a longstanding class of security issues +based on time-of-check, time-of-use races when accessing symbolic links. +.TP +.IR /proc/sys/fs/suid_dumpable " (since Linux 2.6.13)" +.\" The following is based on text from Documentation/sysctl/kernel.txt +The value in this file is assigned to a process's "dumpable" flag +in the circumstances described in +.BR prctl (2). +In effect, +the value in this file determines whether core dump files are +produced for set-user-ID or otherwise protected/tainted binaries. +The "dumpable" setting also affects the ownership of files in a process's +.IR /proc/ pid +directory, as described above. +.IP +Three different integer values can be specified: +.RS +.TP +\fI0\ (default)\fP +.\" In kernel source: SUID_DUMP_DISABLE +This provides the traditional (pre-Linux 2.6.13) behavior. +A core dump will not be produced for a process which has +changed credentials (by calling +.BR seteuid (2), +.BR setgid (2), +or similar, or by executing a set-user-ID or set-group-ID program) +or whose binary does not have read permission enabled. +.TP +\fI1\ ("debug")\fP +.\" In kernel source: SUID_DUMP_USER +All processes dump core when possible. +(Reasons why a process might nevertheless not dump core are described in +.BR core (5).) +The core dump is owned by the filesystem user ID of the dumping process +and no security is applied. +This is intended for system debugging situations only: +this mode is insecure because it allows unprivileged users to +examine the memory contents of privileged processes. +.TP +\fI2\ ("suidsafe")\fP +.\" In kernel source: SUID_DUMP_ROOT +Any binary which normally would not be dumped (see "0" above) +is dumped readable by root only. +This allows the user to remove the core dump file but not to read it. +For security reasons core dumps in this mode will not overwrite one +another or other files. +This mode is appropriate when administrators are +attempting to debug problems in a normal environment. +.IP +Additionally, since Linux 3.6, +.\" 9520628e8ceb69fa9a4aee6b57f22675d9e1b709 +.I /proc/sys/kernel/core_pattern +must either be an absolute pathname +or a pipe command, as detailed in +.BR core (5). +Warnings will be written to the kernel log if +.I core_pattern +does not follow these rules, and no core dump will be produced. +.\" 54b501992dd2a839e94e76aa392c392b55080ce8 +.RE +.IP +For details of the effect of a process's "dumpable" setting +on ptrace access mode checking, see +.BR ptrace (2). +.TP +.I /proc/sys/fs/super\-max +This file +controls the maximum number of superblocks, and +thus the maximum number of mounted filesystems the kernel +can have. +You need increase only +.I super\-max +if you need to mount more filesystems than the current value in +.I super\-max +allows you to. +.TP +.I /proc/sys/fs/super\-nr +This file +contains the number of filesystems currently mounted. +.TP +.I /proc/sys/kernel +This directory contains files controlling a range of kernel parameters, +as described below. +.TP +.I /proc/sys/kernel/acct +This file +contains three numbers: +.IR highwater , +.IR lowwater , +and +.IR frequency . +If BSD-style process accounting is enabled, these values control +its behavior. +If free space on filesystem where the log lives goes below +.I lowwater +percent, accounting suspends. +If free space gets above +.I highwater +percent, accounting resumes. +.I frequency +determines +how often the kernel checks the amount of free space (value is in +seconds). +Default values are 4, 2, and 30. +That is, suspend accounting if 2% or less space is free; resume it +if 4% or more space is free; consider information about amount of free space +valid for 30 seconds. +.TP +.IR /proc/sys/kernel/auto_msgmni " (Linux 2.6.27 to Linux 3.18)" +.\" commit 9eefe520c814f6f62c5d36a2ddcd3fb99dfdb30e (introduces feature) +.\" commit 0050ee059f7fc86b1df2527aaa14ed5dc72f9973 (rendered redundant) +From Linux 2.6.27 to Linux 3.18, +this file was used to control recomputing of the value in +.I /proc/sys/kernel/msgmni +upon the addition or removal of memory or upon IPC namespace creation/removal. +Echoing "1" into this file enabled +.I msgmni +automatic recomputing (and triggered a recomputation of +.I msgmni +based on the current amount of available memory and number of IPC namespaces). +Echoing "0" disabled automatic recomputing. +(Automatic recomputing was also disabled if a value was explicitly assigned to +.IR /proc/sys/kernel/msgmni .) +The default value in +.I auto_msgmni +was 1. +.IP +Since Linux 3.19, the content of this file has no effect (because +.I msgmni +.\" FIXME Must document the 3.19 'msgmni' changes. +defaults to near the maximum value possible), +and reads from this file always return the value "0". +.TP +.IR /proc/sys/kernel/cap_last_cap " (since Linux 3.2)" +See +.BR capabilities (7). +.TP +.IR /proc/sys/kernel/cap\-bound " (from Linux 2.2 to Linux 2.6.24)" +This file holds the value of the kernel +.I "capability bounding set" +(expressed as a signed decimal number). +This set is ANDed against the capabilities permitted to a process +during +.BR execve (2). +Starting with Linux 2.6.25, +the system-wide capability bounding set disappeared, +and was replaced by a per-thread bounding set; see +.BR capabilities (7). +.TP +.I /proc/sys/kernel/core_pattern +See +.BR core (5). +.TP +.I /proc/sys/kernel/core_pipe_limit +See +.BR core (5). +.TP +.I /proc/sys/kernel/core_uses_pid +See +.BR core (5). +.TP +.I /proc/sys/kernel/ctrl\-alt\-del +This file +controls the handling of Ctrl-Alt-Del from the keyboard. +When the value in this file is 0, Ctrl-Alt-Del is trapped and +sent to the +.BR init (1) +program to handle a graceful restart. +When the value is greater than zero, Linux's reaction to a Vulcan +Nerve Pinch (tm) will be an immediate reboot, without even +syncing its dirty buffers. +Note: when a program (like dosemu) has the keyboard in "raw" +mode, the Ctrl-Alt-Del is intercepted by the program before it +ever reaches the kernel tty layer, and it's up to the program +to decide what to do with it. +.TP +.IR /proc/sys/kernel/dmesg_restrict " (since Linux 2.6.37)" +The value in this file determines who can see kernel syslog contents. +A value of 0 in this file imposes no restrictions. +If the value is 1, only privileged users can read the kernel syslog. +(See +.BR syslog (2) +for more details.) +Since Linux 3.4, +.\" commit 620f6e8e855d6d447688a5f67a4e176944a084e8 +only users with the +.B CAP_SYS_ADMIN +capability may change the value in this file. +.TP +.IR /proc/sys/kernel/domainname " and " /proc/sys/kernel/hostname +can be used to set the NIS/YP domainname and the +hostname of your box in exactly the same way as the commands +.BR domainname (1) +and +.BR hostname (1), +that is: +.IP +.in +4n +.EX +.RB "#" " echo \[aq]darkstar\[aq] > /proc/sys/kernel/hostname" +.RB "#" " echo \[aq]mydomain\[aq] > /proc/sys/kernel/domainname" +.EE +.in +.IP +has the same effect as +.IP +.in +4n +.EX +.RB "#" " hostname \[aq]darkstar\[aq]" +.RB "#" " domainname \[aq]mydomain\[aq]" +.EE +.in +.IP +Note, however, that the classic darkstar.frop.org has the +hostname "darkstar" and DNS (Internet Domain Name Server) +domainname "frop.org", not to be confused with the NIS (Network +Information Service) or YP (Yellow Pages) domainname. +These two +domain names are in general different. +For a detailed discussion +see the +.BR hostname (1) +man page. +.TP +.I /proc/sys/kernel/hotplug +This file +contains the pathname for the hotplug policy agent. +The default value in this file is +.IR /sbin/hotplug . +.TP +.\" Removed in commit 87f504e5c78b910b0c1d6ffb89bc95e492322c84 (tglx/history.git) +.IR /proc/sys/kernel/htab\-reclaim " (before Linux 2.4.9.2)" +(PowerPC only) If this file is set to a nonzero value, +the PowerPC htab +.\" removed in commit 1b483a6a7b2998e9c98ad985d7494b9b725bd228, before Linux 2.6.28 +(see kernel file +.IR Documentation/powerpc/ppc_htab.txt ) +is pruned +each time the system hits the idle loop. +.TP +.I /proc/sys/kernel/keys/* +This directory contains various files that define parameters and limits +for the key-management facility. +These files are described in +.BR keyrings (7). +.TP +.IR /proc/sys/kernel/kptr_restrict " (since Linux 2.6.38)" +.\" 455cd5ab305c90ffc422dd2e0fb634730942b257 +The value in this file determines whether kernel addresses are exposed via +.I /proc +files and other interfaces. +A value of 0 in this file imposes no restrictions. +If the value is 1, kernel pointers printed using the +.I %pK +format specifier will be replaced with zeros unless the user has the +.B CAP_SYSLOG +capability. +If the value is 2, kernel pointers printed using the +.I %pK +format specifier will be replaced with zeros regardless +of the user's capabilities. +The initial default value for this file was 1, +but the default was changed +.\" commit 411f05f123cbd7f8aa1edcae86970755a6e2a9d9 +to 0 in Linux 2.6.39. +Since Linux 3.4, +.\" commit 620f6e8e855d6d447688a5f67a4e176944a084e8 +only users with the +.B CAP_SYS_ADMIN +capability can change the value in this file. +.TP +.I /proc/sys/kernel/l2cr +(PowerPC only) This file +contains a flag that controls the L2 cache of G3 processor +boards. +If 0, the cache is disabled. +Enabled if nonzero. +.TP +.I /proc/sys/kernel/modprobe +This file contains the pathname for the kernel module loader. +The default value is +.IR /sbin/modprobe . +The file is present only if the kernel is built with the +.B CONFIG_MODULES +.RB ( CONFIG_KMOD +in Linux 2.6.26 and earlier) +option enabled. +It is described by the Linux kernel source file +.I Documentation/kmod.txt +(present only in Linux 2.4 and earlier). +.TP +.IR /proc/sys/kernel/modules_disabled " (since Linux 2.6.31)" +.\" 3d43321b7015387cfebbe26436d0e9d299162ea1 +.\" From Documentation/sysctl/kernel.txt +A toggle value indicating if modules are allowed to be loaded +in an otherwise modular kernel. +This toggle defaults to off (0), but can be set true (1). +Once true, modules can be neither loaded nor unloaded, +and the toggle cannot be set back to false. +The file is present only if the kernel is built with the +.B CONFIG_MODULES +option enabled. +.TP +.IR /proc/sys/kernel/msgmax " (since Linux 2.2)" +This file defines +a system-wide limit specifying the maximum number of bytes in +a single message written on a System V message queue. +.TP +.IR /proc/sys/kernel/msgmni " (since Linux 2.4)" +This file defines the system-wide limit on the number of +message queue identifiers. +See also +.IR /proc/sys/kernel/auto_msgmni . +.TP +.IR /proc/sys/kernel/msgmnb " (since Linux 2.2)" +This file defines a system-wide parameter used to initialize the +.I msg_qbytes +setting for subsequently created message queues. +The +.I msg_qbytes +setting specifies the maximum number of bytes that may be written to the +message queue. +.TP +.IR /proc/sys/kernel/ngroups_max " (since Linux 2.6.4)" +This is a read-only file that displays the upper limit on the +number of a process's group memberships. +.TP +.IR /proc/sys/kernel/ns_last_pid " (since Linux 3.3)" +See +.BR pid_namespaces (7). +.TP +.IR /proc/sys/kernel/ostype " and " /proc/sys/kernel/osrelease +These files +give substrings of +.IR /proc/version . +.TP +.IR /proc/sys/kernel/overflowgid " and " /proc/sys/kernel/overflowuid +These files duplicate the files +.I /proc/sys/fs/overflowgid +and +.IR /proc/sys/fs/overflowuid . +.TP +.I /proc/sys/kernel/panic +This file gives read/write access to the kernel variable +.IR panic_timeout . +If this is zero, the kernel will loop on a panic; if nonzero, +it indicates that the kernel should autoreboot after this number +of seconds. +When you use the +software watchdog device driver, the recommended setting is 60. +.TP +.IR /proc/sys/kernel/panic_on_oops " (since Linux 2.5.68)" +This file controls the kernel's behavior when an oops +or BUG is encountered. +If this file contains 0, then the system +tries to continue operation. +If it contains 1, then the system +delays a few seconds (to give klogd time to record the oops output) +and then panics. +If the +.I /proc/sys/kernel/panic +file is also nonzero, then the machine will be rebooted. +.TP +.IR /proc/sys/kernel/pid_max " (since Linux 2.5.34)" +This file specifies the value at which PIDs wrap around +(i.e., the value in this file is one greater than the maximum PID). +PIDs greater than this value are not allocated; +thus, the value in this file also acts as a system-wide limit +on the total number of processes and threads. +The default value for this file, 32768, +results in the same range of PIDs as on earlier kernels. +On 32-bit platforms, 32768 is the maximum value for +.IR pid_max . +On 64-bit systems, +.I pid_max +can be set to any value up to 2\[ha]22 +.RB ( PID_MAX_LIMIT , +approximately 4 million). +.\" Prior to Linux 2.6.10, pid_max could also be raised above 32768 on 32-bit +.\" platforms, but this broke /proc/[pid] +.\" See http://marc.theaimsgroup.com/?l=linux-kernel&m=109513010926152&w=2 +.TP +.IR /proc/sys/kernel/powersave\-nap " (PowerPC only)" +This file contains a flag. +If set, Linux-PPC will use the "nap" mode of +powersaving, +otherwise the "doze" mode will be used. +.TP +.I /proc/sys/kernel/printk +See +.BR syslog (2). +.TP +.IR /proc/sys/kernel/pty " (since Linux 2.6.4)" +This directory contains two files relating to the number of UNIX 98 +pseudoterminals (see +.BR pts (4)) +on the system. +.TP +.I /proc/sys/kernel/pty/max +This file defines the maximum number of pseudoterminals. +.\" FIXME Document /proc/sys/kernel/pty/reserve +.\" New in Linux 3.3 +.\" commit e9aba5158a80098447ff207a452a3418ae7ee386 +.TP +.I /proc/sys/kernel/pty/nr +This read-only file +indicates how many pseudoterminals are currently in use. +.TP +.I /proc/sys/kernel/random +This directory +contains various parameters controlling the operation of the file +.IR /dev/random . +See +.BR random (4) +for further information. +.TP +.IR /proc/sys/kernel/random/uuid " (since Linux 2.4)" +Each read from this read-only file returns a randomly generated 128-bit UUID, +as a string in the standard UUID format. +.TP +.IR /proc/sys/kernel/randomize_va_space " (since Linux 2.6.12)" +.\" Some further details can be found in Documentation/sysctl/kernel.txt +Select the address space layout randomization (ASLR) policy for the system +(on architectures that support ASLR). +Three values are supported for this file: +.RS +.TP +.B 0 +Turn ASLR off. +This is the default for architectures that don't support ASLR, +and when the kernel is booted with the +.I norandmaps +parameter. +.TP +.B 1 +Make the addresses of +.BR mmap (2) +allocations, the stack, and the VDSO page randomized. +Among other things, this means that shared libraries will be +loaded at randomized addresses. +The text segment of PIE-linked binaries will also be loaded +at a randomized address. +This value is the default if the kernel was configured with +.BR CONFIG_COMPAT_BRK . +.TP +.B 2 +(Since Linux 2.6.25) +.\" commit c1d171a002942ea2d93b4fbd0c9583c56fce0772 +Also support heap randomization. +This value is the default if the kernel was not configured with +.BR CONFIG_COMPAT_BRK . +.RE +.TP +.I /proc/sys/kernel/real\-root\-dev +This file is documented in the Linux kernel source file +.I Documentation/admin\-guide/initrd.rst +.\" commit 9d85025b0418163fae079c9ba8f8445212de8568 +(or +.I Documentation/initrd.txt +before Linux 4.10). +.TP +.IR /proc/sys/kernel/reboot\-cmd " (Sparc only)" +This file seems to be a way to give an argument to the SPARC +ROM/Flash boot loader. +Maybe to tell it what to do after +rebooting? +.TP +.I /proc/sys/kernel/rtsig\-max +(Up to and including Linux 2.6.7; see +.BR setrlimit (2)) +This file can be used to tune the maximum number +of POSIX real-time (queued) signals that can be outstanding +in the system. +.TP +.I /proc/sys/kernel/rtsig\-nr +(Up to and including Linux 2.6.7.) +This file shows the number of POSIX real-time signals currently queued. +.TP +.IR /proc/ pid /sched_autogroup_enabled " (since Linux 2.6.38)" +.\" commit 5091faa449ee0b7d73bc296a93bca9540fc51d0a +See +.BR sched (7). +.TP +.IR /proc/sys/kernel/sched_child_runs_first " (since Linux 2.6.23)" +If this file contains the value zero, then, after a +.BR fork (2), +the parent is first scheduled on the CPU. +If the file contains a nonzero value, +then the child is scheduled first on the CPU. +(Of course, on a multiprocessor system, +the parent and the child might both immediately be scheduled on a CPU.) +.TP +.IR /proc/sys/kernel/sched_rr_timeslice_ms " (since Linux 3.9)" +See +.BR sched_rr_get_interval (2). +.TP +.IR /proc/sys/kernel/sched_rt_period_us " (since Linux 2.6.25)" +See +.BR sched (7). +.TP +.IR /proc/sys/kernel/sched_rt_runtime_us " (since Linux 2.6.25)" +See +.BR sched (7). +.TP +.IR /proc/sys/kernel/seccomp " (since Linux 4.14)" +.\" commit 8e5f1ad116df6b0de65eac458d5e7c318d1c05af +This directory provides additional seccomp information and +configuration. +See +.BR seccomp (2) +for further details. +.TP +.IR /proc/sys/kernel/sem " (since Linux 2.4)" +This file contains 4 numbers defining limits for System V IPC semaphores. +These fields are, in order: +.RS +.TP +SEMMSL +The maximum semaphores per semaphore set. +.TP +SEMMNS +A system-wide limit on the number of semaphores in all semaphore sets. +.TP +SEMOPM +The maximum number of operations that may be specified in a +.BR semop (2) +call. +.TP +SEMMNI +A system-wide limit on the maximum number of semaphore identifiers. +.RE +.TP +.I /proc/sys/kernel/sg\-big\-buff +This file +shows the size of the generic SCSI device (sg) buffer. +You can't tune it just yet, but you could change it at +compile time by editing +.I include/scsi/sg.h +and changing +the value of +.BR SG_BIG_BUFF . +However, there shouldn't be any reason to change this value. +.TP +.IR /proc/sys/kernel/shm_rmid_forced " (since Linux 3.1)" +.\" commit b34a6b1da371ed8af1221459a18c67970f7e3d53 +.\" See also Documentation/sysctl/kernel.txt +If this file is set to 1, all System V shared memory segments will +be marked for destruction as soon as the number of attached processes +falls to zero; +in other words, it is no longer possible to create shared memory segments +that exist independently of any attached process. +.IP +The effect is as though a +.BR shmctl (2) +.B IPC_RMID +is performed on all existing segments as well as all segments +created in the future (until this file is reset to 0). +Note that existing segments that are attached to no process will be +immediately destroyed when this file is set to 1. +Setting this option will also destroy segments that were created, +but never attached, +upon termination of the process that created the segment with +.BR shmget (2). +.IP +Setting this file to 1 provides a way of ensuring that +all System V shared memory segments are counted against the +resource usage and resource limits (see the description of +.B RLIMIT_AS +in +.BR getrlimit (2)) +of at least one process. +.IP +Because setting this file to 1 produces behavior that is nonstandard +and could also break existing applications, +the default value in this file is 0. +Set this file to 1 only if you have a good understanding +of the semantics of the applications using +System V shared memory on your system. +.TP +.IR /proc/sys/kernel/shmall " (since Linux 2.2)" +This file +contains the system-wide limit on the total number of pages of +System V shared memory. +.TP +.IR /proc/sys/kernel/shmmax " (since Linux 2.2)" +This file +can be used to query and set the run-time limit +on the maximum (System V IPC) shared memory segment size that can be +created. +Shared memory segments up to 1 GB are now supported in the +kernel. +This value defaults to +.BR SHMMAX . +.TP +.IR /proc/sys/kernel/shmmni " (since Linux 2.4)" +This file +specifies the system-wide maximum number of System V shared memory +segments that can be created. +.TP +.IR /proc/sys/kernel/sysctl_writes_strict " (since Linux 3.16)" +.\" commit f88083005ab319abba5d0b2e4e997558245493c8 +.\" commit 2ca9bb456ada8bcbdc8f77f8fc78207653bbaa92 +.\" commit f4aacea2f5d1a5f7e3154e967d70cf3f711bcd61 +.\" commit 24fe831c17ab8149413874f2fd4e5c8a41fcd294 +The value in this file determines how the file offset affects +the behavior of updating entries in files under +.IR /proc/sys . +The file has three possible values: +.RS +.TP 4 +\-1 +This provides legacy handling, with no printk warnings. +Each +.BR write (2) +must fully contain the value to be written, +and multiple writes on the same file descriptor +will overwrite the entire value, regardless of the file position. +.TP +0 +(default) This provides the same behavior as for \-1, +but printk warnings are written for processes that +perform writes when the file offset is not 0. +.TP +1 +Respect the file offset when writing strings into +.I /proc/sys +files. +Multiple writes will +.I append +to the value buffer. +Anything written beyond the maximum length +of the value buffer will be ignored. +Writes to numeric +.I /proc/sys +entries must always be at file offset 0 and the value must be +fully contained in the buffer provided to +.BR write (2). +.\" FIXME . +.\" With /proc/sys/kernel/sysctl_writes_strict==1, writes at an +.\" offset other than 0 do not generate an error. Instead, the +.\" write() succeeds, but the file is left unmodified. +.\" This is surprising. The behavior may change in the future. +.\" See thread.gmane.org/gmane.linux.man/9197 +.\" From: Michael Kerrisk (man-pages <mtk.manpages@...> +.\" Subject: sysctl_writes_strict documentation + an oddity? +.\" Newsgroups: gmane.linux.man, gmane.linux.kernel +.\" Date: 2015-05-09 08:54:11 GMT +.RE +.TP +.I /proc/sys/kernel/sysrq +This file controls the functions allowed to be invoked by the SysRq key. +By default, +the file contains 1 meaning that every possible SysRq request is allowed +(in older kernel versions, SysRq was disabled by default, +and you were required to specifically enable it at run-time, +but this is not the case any more). +Possible values in this file are: +.RS +.TP 5 +0 +Disable sysrq completely +.TP +1 +Enable all functions of sysrq +.TP +> 1 +Bit mask of allowed sysrq functions, as follows: +.PD 0 +.RS +.TP 5 +\ \ 2 +Enable control of console logging level +.TP +\ \ 4 +Enable control of keyboard (SAK, unraw) +.TP +\ \ 8 +Enable debugging dumps of processes etc. +.TP +\ 16 +Enable sync command +.TP +\ 32 +Enable remount read-only +.TP +\ 64 +Enable signaling of processes (term, kill, oom-kill) +.TP +128 +Allow reboot/poweroff +.TP +256 +Allow nicing of all real-time tasks +.RE +.PD +.RE +.IP +This file is present only if the +.B CONFIG_MAGIC_SYSRQ +kernel configuration option is enabled. +For further details see the Linux kernel source file +.I Documentation/admin\-guide/sysrq.rst +.\" commit 9d85025b0418163fae079c9ba8f8445212de8568 +(or +.I Documentation/sysrq.txt +before Linux 4.10). +.TP +.I /proc/sys/kernel/version +This file contains a string such as: +.IP +.in +4n +.EX +#5 Wed Feb 25 21:49:24 MET 1998 +.EE +.in +.IP +The "#5" means that +this is the fifth kernel built from this source base and the +date following it indicates the time the kernel was built. +.TP +.IR /proc/sys/kernel/threads\-max " (since Linux 2.3.11)" +.\" The following is based on Documentation/sysctl/kernel.txt +This file specifies the system-wide limit on the number of +threads (tasks) that can be created on the system. +.IP +Since Linux 4.1, +.\" commit 230633d109e35b0a24277498e773edeb79b4a331 +the value that can be written to +.I threads\-max +is bounded. +The minimum value that can be written is 20. +The maximum value that can be written is given by the +constant +.B FUTEX_TID_MASK +(0x3fffffff). +If a value outside of this range is written to +.IR threads\-max , +the error +.B EINVAL +occurs. +.IP +The value written is checked against the available RAM pages. +If the thread structures would occupy too much (more than 1/8th) +of the available RAM pages, +.I threads\-max +is reduced accordingly. +.TP +.IR /proc/sys/kernel/yama/ptrace_scope " (since Linux 3.5)" +See +.BR ptrace (2). +.TP +.IR /proc/sys/kernel/zero\-paged " (PowerPC only)" +This file +contains a flag. +When enabled (nonzero), Linux-PPC will pre-zero pages in +the idle loop, possibly speeding up get_free_pages. +.TP +.I /proc/sys/net +This directory contains networking stuff. +Explanations for some of the files under this directory can be found in +.BR tcp (7) +and +.BR ip (7). +.TP +.I /proc/sys/net/core/bpf_jit_enable +See +.BR bpf (2). +.TP +.I /proc/sys/net/core/somaxconn +This file defines a ceiling value for the +.I backlog +argument of +.BR listen (2); +see the +.BR listen (2) +manual page for details. +.TP +.I /proc/sys/proc +This directory may be empty. +.TP +.I /proc/sys/sunrpc +This directory supports Sun remote procedure call for network filesystem +(NFS). +On some systems, it is not present. +.TP +.IR /proc/sys/user " (since Linux 4.9)" +See +.BR namespaces (7). +.TP +.I /proc/sys/vm +This directory contains files for memory management tuning, buffer, and +cache management. +.TP +.IR /proc/sys/vm/admin_reserve_kbytes " (since Linux 3.10)" +.\" commit 4eeab4f5580d11bffedc697684b91b0bca0d5009 +This file defines the amount of free memory (in KiB) on the system that +should be reserved for users with the capability +.BR CAP_SYS_ADMIN . +.IP +The default value in this file is the minimum of [3% of free pages, 8MiB] +expressed as KiB. +The default is intended to provide enough for the superuser +to log in and kill a process, if necessary, +under the default overcommit 'guess' mode (i.e., 0 in +.IR /proc/sys/vm/overcommit_memory ). +.IP +Systems running in "overcommit never" mode (i.e., 2 in +.IR /proc/sys/vm/overcommit_memory ) +should increase the value in this file to account +for the full virtual memory size of the programs used to recover (e.g., +.BR login (1) +.BR ssh (1), +and +.BR top (1)) +Otherwise, the superuser may not be able to log in to recover the system. +For example, on x86-64 a suitable value is 131072 (128MiB reserved). +.IP +Changing the value in this file takes effect whenever +an application requests memory. +.TP +.IR /proc/sys/vm/compact_memory " (since Linux 2.6.35)" +When 1 is written to this file, all zones are compacted such that free +memory is available in contiguous blocks where possible. +The effect of this action can be seen by examining +.IR /proc/buddyinfo . +.IP +Present only if the kernel was configured with +.BR CONFIG_COMPACTION . +.TP +.IR /proc/sys/vm/drop_caches " (since Linux 2.6.16)" +Writing to this file causes the kernel to drop clean caches, dentries, and +inodes from memory, causing that memory to become free. +This can be useful for memory management testing and +performing reproducible filesystem benchmarks. +Because writing to this file causes the benefits of caching to be lost, +it can degrade overall system performance. +.IP +To free pagecache, use: +.IP +.in +4n +.EX +echo 1 > /proc/sys/vm/drop_caches +.EE +.in +.IP +To free dentries and inodes, use: +.IP +.in +4n +.EX +echo 2 > /proc/sys/vm/drop_caches +.EE +.in +.IP +To free pagecache, dentries, and inodes, use: +.IP +.in +4n +.EX +echo 3 > /proc/sys/vm/drop_caches +.EE +.in +.IP +Because writing to this file is a nondestructive operation and dirty objects +are not freeable, the +user should run +.BR sync (1) +first. +.TP +.IR /proc/sys/vm/sysctl_hugetlb_shm_group " (since Linux 2.6.7)" +This writable file contains a group ID that is allowed +to allocate memory using huge pages. +If a process has a filesystem group ID or any supplementary group ID that +matches this group ID, +then it can make huge-page allocations without holding the +.B CAP_IPC_LOCK +capability; see +.BR memfd_create (2), +.BR mmap (2), +and +.BR shmget (2). +.TP +.IR /proc/sys/vm/legacy_va_layout " (since Linux 2.6.9)" +.\" The following is from Documentation/filesystems/proc.txt +If nonzero, this disables the new 32-bit memory-mapping layout; +the kernel will use the legacy (2.4) layout for all processes. +.TP +.IR /proc/sys/vm/memory_failure_early_kill " (since Linux 2.6.32)" +.\" The following is based on the text in Documentation/sysctl/vm.txt +Control how to kill processes when an uncorrected memory error +(typically a 2-bit error in a memory module) +that cannot be handled by the kernel +is detected in the background by hardware. +In some cases (like the page still having a valid copy on disk), +the kernel will handle the failure +transparently without affecting any applications. +But if there is no other up-to-date copy of the data, +it will kill processes to prevent any data corruptions from propagating. +.IP +The file has one of the following values: +.RS +.TP +.B 1 +Kill all processes that have the corrupted-and-not-reloadable page mapped +as soon as the corruption is detected. +Note that this is not supported for a few types of pages, +such as kernel internally +allocated data or the swap cache, but works for the majority of user pages. +.TP +.B 0 +Unmap the corrupted page from all processes and kill a process +only if it tries to access the page. +.RE +.IP +The kill is performed using a +.B SIGBUS +signal with +.I si_code +set to +.BR BUS_MCEERR_AO . +Processes can handle this if they want to; see +.BR sigaction (2) +for more details. +.IP +This feature is active only on architectures/platforms with advanced machine +check handling and depends on the hardware capabilities. +.IP +Applications can override the +.I memory_failure_early_kill +setting individually with the +.BR prctl (2) +.B PR_MCE_KILL +operation. +.IP +Present only if the kernel was configured with +.BR CONFIG_MEMORY_FAILURE . +.TP +.IR /proc/sys/vm/memory_failure_recovery " (since Linux 2.6.32)" +.\" The following is based on the text in Documentation/sysctl/vm.txt +Enable memory failure recovery (when supported by the platform). +.RS +.TP +.B 1 +Attempt recovery. +.TP +.B 0 +Always panic on a memory failure. +.RE +.IP +Present only if the kernel was configured with +.BR CONFIG_MEMORY_FAILURE . +.TP +.IR /proc/sys/vm/oom_dump_tasks " (since Linux 2.6.25)" +.\" The following is from Documentation/sysctl/vm.txt +Enables a system-wide task dump (excluding kernel threads) to be +produced when the kernel performs an OOM-killing. +The dump includes the following information +for each task (thread, process): +thread ID, real user ID, thread group ID (process ID), +virtual memory size, resident set size, +the CPU that the task is scheduled on, +oom_adj score (see the description of +.IR /proc/ pid /oom_adj ), +and command name. +This is helpful to determine why the OOM-killer was invoked +and to identify the rogue task that caused it. +.IP +If this contains the value zero, this information is suppressed. +On very large systems with thousands of tasks, +it may not be feasible to dump the memory state information for each one. +Such systems should not be forced to incur a performance penalty in +OOM situations when the information may not be desired. +.IP +If this is set to nonzero, this information is shown whenever the +OOM-killer actually kills a memory-hogging task. +.IP +The default value is 0. +.TP +.IR /proc/sys/vm/oom_kill_allocating_task " (since Linux 2.6.24)" +.\" The following is from Documentation/sysctl/vm.txt +This enables or disables killing the OOM-triggering task in +out-of-memory situations. +.IP +If this is set to zero, the OOM-killer will scan through the entire +tasklist and select a task based on heuristics to kill. +This normally selects a rogue memory-hogging task that +frees up a large amount of memory when killed. +.IP +If this is set to nonzero, the OOM-killer simply kills the task that +triggered the out-of-memory condition. +This avoids a possibly expensive tasklist scan. +.IP +If +.I /proc/sys/vm/panic_on_oom +is nonzero, it takes precedence over whatever value is used in +.IR /proc/sys/vm/oom_kill_allocating_task . +.IP +The default value is 0. +.TP +.IR /proc/sys/vm/overcommit_kbytes " (since Linux 3.14)" +.\" commit 49f0ce5f92321cdcf741e35f385669a421013cb7 +This writable file provides an alternative to +.I /proc/sys/vm/overcommit_ratio +for controlling the +.I CommitLimit +when +.I /proc/sys/vm/overcommit_memory +has the value 2. +It allows the amount of memory overcommitting to be specified as +an absolute value (in kB), +rather than as a percentage, as is done with +.IR overcommit_ratio . +This allows for finer-grained control of +.I CommitLimit +on systems with extremely large memory sizes. +.IP +Only one of +.I overcommit_kbytes +or +.I overcommit_ratio +can have an effect: +if +.I overcommit_kbytes +has a nonzero value, then it is used to calculate +.IR CommitLimit , +otherwise +.I overcommit_ratio +is used. +Writing a value to either of these files causes the +value in the other file to be set to zero. +.TP +.I /proc/sys/vm/overcommit_memory +This file contains the kernel virtual memory accounting mode. +Values are: +.RS +.IP +0: heuristic overcommit (this is the default) +.br +1: always overcommit, never check +.br +2: always check, never overcommit +.RE +.IP +In mode 0, calls of +.BR mmap (2) +with +.B MAP_NORESERVE +are not checked, and the default check is very weak, +leading to the risk of getting a process "OOM-killed". +.IP +In mode 1, the kernel pretends there is always enough memory, +until memory actually runs out. +One use case for this mode is scientific computing applications +that employ large sparse arrays. +Before Linux 2.6.0, any nonzero value implies mode 1. +.IP +In mode 2 (available since Linux 2.6), the total virtual address space +that can be allocated +.RI ( CommitLimit +in +.IR /proc/meminfo ) +is calculated as +.IP +.in +4n +.EX +CommitLimit = (total_RAM \- total_huge_TLB) * + overcommit_ratio / 100 + total_swap +.EE +.in +.IP +where: +.RS +.IP \[bu] 3 +.I total_RAM +is the total amount of RAM on the system; +.IP \[bu] +.I total_huge_TLB +is the amount of memory set aside for huge pages; +.IP \[bu] +.I overcommit_ratio +is the value in +.IR /proc/sys/vm/overcommit_ratio ; +and +.IP \[bu] +.I total_swap +is the amount of swap space. +.RE +.IP +For example, on a system with 16 GB of physical RAM, 16 GB +of swap, no space dedicated to huge pages, and an +.I overcommit_ratio +of 50, this formula yields a +.I CommitLimit +of 24 GB. +.IP +Since Linux 3.14, if the value in +.I /proc/sys/vm/overcommit_kbytes +is nonzero, then +.I CommitLimit +is instead calculated as: +.IP +.in +4n +.EX +CommitLimit = overcommit_kbytes + total_swap +.EE +.in +.IP +See also the description of +.I /proc/sys/vm/admin_reserve_kbytes +and +.IR /proc/sys/vm/user_reserve_kbytes . +.TP +.IR /proc/sys/vm/overcommit_ratio " (since Linux 2.6.0)" +This writable file defines a percentage by which memory +can be overcommitted. +The default value in the file is 50. +See the description of +.IR /proc/sys/vm/overcommit_memory . +.TP +.IR /proc/sys/vm/panic_on_oom " (since Linux 2.6.18)" +.\" The following is adapted from Documentation/sysctl/vm.txt +This enables or disables a kernel panic in +an out-of-memory situation. +.IP +If this file is set to the value 0, +the kernel's OOM-killer will kill some rogue process. +Usually, the OOM-killer is able to kill a rogue process and the +system will survive. +.IP +If this file is set to the value 1, +then the kernel normally panics when out-of-memory happens. +However, if a process limits allocations to certain nodes +using memory policies +.RB ( mbind (2) +.BR MPOL_BIND ) +or cpusets +.RB ( cpuset (7)) +and those nodes reach memory exhaustion status, +one process may be killed by the OOM-killer. +No panic occurs in this case: +because other nodes' memory may be free, +this means the system as a whole may not have reached +an out-of-memory situation yet. +.IP +If this file is set to the value 2, +the kernel always panics when an out-of-memory condition occurs. +.IP +The default value is 0. +1 and 2 are for failover of clustering. +Select either according to your policy of failover. +.TP +.I /proc/sys/vm/swappiness +.\" The following is from Documentation/sysctl/vm.txt +The value in this file controls how aggressively the kernel will swap +memory pages. +Higher values increase aggressiveness, lower values +decrease aggressiveness. +The default value is 60. +.TP +.IR /proc/sys/vm/user_reserve_kbytes " (since Linux 3.10)" +.\" commit c9b1d0981fcce3d9976d7b7a56e4e0503bc610dd +Specifies an amount of memory (in KiB) to reserve for user processes. +This is intended to prevent a user from starting a single memory hogging +process, such that they cannot recover (kill the hog). +The value in this file has an effect only when +.I /proc/sys/vm/overcommit_memory +is set to 2 ("overcommit never" mode). +In this case, the system reserves an amount of memory that is the minimum +of [3% of current process size, +.IR user_reserve_kbytes ]. +.IP +The default value in this file is the minimum of [3% of free pages, 128MiB] +expressed as KiB. +.IP +If the value in this file is set to zero, +then a user will be allowed to allocate all free memory with a single process +(minus the amount reserved by +.IR /proc/sys/vm/admin_reserve_kbytes ). +Any subsequent attempts to execute a command will result in +"fork: Cannot allocate memory". +.IP +Changing the value in this file takes effect whenever +an application requests memory. +.TP +.IR /proc/sys/vm/unprivileged_userfaultfd " (since Linux 5.2)" +.\" cefdca0a86be517bc390fc4541e3674b8e7803b0 +This (writable) file exposes a flag that controls whether +unprivileged processes are allowed to employ +.BR userfaultfd (2). +If this file has the value 1, then unprivileged processes may use +.BR userfaultfd (2). +If this file has the value 0, then only processes that have the +.B CAP_SYS_PTRACE +capability may employ +.BR userfaultfd (2). +The default value in this file is 1. +.TP +.IR /proc/sysrq\-trigger " (since Linux 2.4.21)" +Writing a character to this file triggers the same SysRq function as +typing ALT-SysRq-<character> (see the description of +.IR /proc/sys/kernel/sysrq ). +This file is normally writable only by +.IR root . +For further details see the Linux kernel source file +.I Documentation/admin\-guide/sysrq.rst +.\" commit 9d85025b0418163fae079c9ba8f8445212de8568 +(or +.I Documentation/sysrq.txt +before Linux 4.10). +.TP +.I /proc/sysvipc +Subdirectory containing the pseudo-files +.IR msg ", " sem " and " shm "." +These files list the System V Interprocess Communication (IPC) objects +(respectively: message queues, semaphores, and shared memory) +that currently exist on the system, +providing similar information to that available via +.BR ipcs (1). +These files have headers and are formatted (one IPC object per line) +for easy understanding. +.BR sysvipc (7) +provides further background on the information shown by these files. +.TP +.IR /proc/thread\-self " (since Linux 3.17)" +.\" commit 0097875bd41528922fb3bb5f348c53f17e00e2fd +This directory refers to the thread accessing the +.I /proc +filesystem, +and is identical to the +.IR /proc/self/task/ tid +directory named by the process thread ID +.RI ( tid ) +of the same thread. +.TP +.IR /proc/timer_list " (since Linux 2.6.21)" +.\" commit 289f480af87e45f7a6de6ba9b4c061c2e259fe98 +This read-only file exposes a list of all currently pending +(high-resolution) timers, +all clock-event sources, and their parameters in a human-readable form. +.TP +.IR /proc/timer_stats " (from Linux 2.6.21 until Linux 4.10)" +.\" commit 82f67cd9fca8c8762c15ba7ed0d5747588c1e221 +.\" Date: Fri Feb 16 01:28:13 2007 -0800 +.\" Text largely derived from Documentation/timers/timer_stats.txt +.\" removed in commit dfb4357da6ddbdf57d583ba64361c9d792b0e0b1 +.\" Date: Wed Feb 8 11:26:59 2017 -0800 +This is a debugging facility to make timer (ab)use in a Linux +system visible to kernel and user-space developers. +It can be used by kernel and user-space developers to verify that +their code does not make undue use of timers. +The goal is to avoid unnecessary wakeups, +thereby optimizing power consumption. +.IP +If enabled in the kernel +.RB ( CONFIG_TIMER_STATS ), +but not used, +it has almost zero run-time overhead and a relatively small +data-structure overhead. +Even if collection is enabled at run time, overhead is low: +all the locking is per-CPU and lookup is hashed. +.IP +The +.I /proc/timer_stats +file is used both to control sampling facility and to read out the +sampled information. +.IP +The +.I timer_stats +functionality is inactive on bootup. +A sampling period can be started using the following command: +.IP +.in +4n +.EX +# echo 1 > /proc/timer_stats +.EE +.in +.IP +The following command stops a sampling period: +.IP +.in +4n +.EX +# echo 0 > /proc/timer_stats +.EE +.in +.IP +The statistics can be retrieved by: +.IP +.in +4n +.EX +$ cat /proc/timer_stats +.EE +.in +.IP +While sampling is enabled, each readout from +.I /proc/timer_stats +will see +newly updated statistics. +Once sampling is disabled, the sampled information +is kept until a new sample period is started. +This allows multiple readouts. +.IP +Sample output from +.IR /proc/timer_stats : +.IP +.in +4n +.EX +.RB $ " cat /proc/timer_stats" +Timer Stats Version: v0.3 +Sample period: 1.764 s +Collection: active + 255, 0 swapper/3 hrtimer_start_range_ns (tick_sched_timer) + 71, 0 swapper/1 hrtimer_start_range_ns (tick_sched_timer) + 58, 0 swapper/0 hrtimer_start_range_ns (tick_sched_timer) + 4, 1694 gnome\-shell mod_delayed_work_on (delayed_work_timer_fn) + 17, 7 rcu_sched rcu_gp_kthread (process_timeout) +\&... + 1, 4911 kworker/u16:0 mod_delayed_work_on (delayed_work_timer_fn) + 1D, 2522 kworker/0:0 queue_delayed_work_on (delayed_work_timer_fn) +1029 total events, 583.333 events/sec +.EE +.in +.IP +The output columns are: +.RS +.IP [1] 5 +a count of the number of events, +optionally (since Linux 2.6.23) followed by the letter \[aq]D\[aq] +.\" commit c5c061b8f9726bc2c25e19dec227933a13d1e6b7 deferrable timers +if this is a deferrable timer; +.IP [2] +the PID of the process that initialized the timer; +.IP [3] +the name of the process that initialized the timer; +.IP [4] +the function where the timer was initialized; and +(in parentheses) +the callback function that is associated with the timer. +.RE +.IP +During the Linux 4.11 development cycle, +this file was removed because of security concerns, +as it exposes information across namespaces. +Furthermore, it is possible to obtain +the same information via in-kernel tracing facilities such as ftrace. +.TP +.I /proc/tty +Subdirectory containing the pseudo-files and subdirectories for +tty drivers and line disciplines. +.TP +.I /proc/uptime +This file contains two numbers (values in seconds): the uptime of the +system (including time spent in suspend) and the amount of time spent +in the idle process. +.TP +.I /proc/version +This string identifies the kernel version that is currently running. +It includes the contents of +.IR /proc/sys/kernel/ostype , +.IR /proc/sys/kernel/osrelease , +and +.IR /proc/sys/kernel/version . +For example: +.IP +.in +4n +.EX +Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994 +.EE +.in +.\" FIXME 2.6.13 seems to have /proc/vmcore implemented; document this +.\" See Documentation/kdump/kdump.txt +.\" commit 666bfddbe8b8fd4fd44617d6c55193d5ac7edb29 +.\" Needs CONFIG_VMCORE +.\" +.TP +.IR /proc/vmstat " (since Linux 2.6.0)" +This file displays various virtual memory statistics. +Each line of this file contains a single name-value pair, +delimited by white space. +Some lines are present only if the kernel was configured with +suitable options. +(In some cases, the options required for particular files have changed +across kernel versions, so they are not listed here. +Details can be found by consulting the kernel source code.) +The following fields may be present: +.\" FIXME We need explanations for each of the following fields... +.RS +.TP +.IR nr_free_pages " (since Linux 2.6.31)" +.\" commit d23ad42324cc4378132e51f2fc5c9ba6cbe75182 +.TP +.IR nr_alloc_batch " (since Linux 3.12)" +.\" commit 81c0a2bb515fd4daae8cab64352877480792b515 +.TP +.IR nr_inactive_anon " (since Linux 2.6.28)" +.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db +.TP +.IR nr_active_anon " (since Linux 2.6.28)" +.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db +.TP +.IR nr_inactive_file " (since Linux 2.6.28)" +.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db +.TP +.IR nr_active_file " (since Linux 2.6.28)" +.\" commit 4f98a2fee8acdb4ac84545df98cccecfd130f8db +.TP +.IR nr_unevictable " (since Linux 2.6.28)" +.\" commit 7b854121eb3e5ba0241882ff939e2c485228c9c5 +.TP +.IR nr_mlock " (since Linux 2.6.28)" +.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820 +.TP +.IR nr_anon_pages " (since Linux 2.6.18)" +.\" commit f3dbd34460ff54962d3e3244b6bcb7f5295356e6 +.TP +.IR nr_mapped " (since Linux 2.6.0)" +.TP +.IR nr_file_pages " (since Linux 2.6.18)" +.\" commit 347ce434d57da80fd5809c0c836f206a50999c26 +.TP +.IR nr_dirty " (since Linux 2.6.0)" +.TP +.IR nr_writeback " (since Linux 2.6.0)" +.TP +.IR nr_slab_reclaimable " (since Linux 2.6.19)" +.\" commit 972d1a7b140569084439a81265a0f15b74e924e0 +.\" Linux 2.6.0 had nr_slab +.TP +.IR nr_slab_unreclaimable " (since Linux 2.6.19)" +.\" commit 972d1a7b140569084439a81265a0f15b74e924e0 +.TP +.IR nr_page_table_pages " (since Linux 2.6.0)" +.TP +.IR nr_kernel_stack " (since Linux 2.6.32)" +.\" commit c6a7f5728a1db45d30df55a01adc130b4ab0327c +Amount of memory allocated to kernel stacks. +.TP +.IR nr_unstable " (since Linux 2.6.0)" +.TP +.IR nr_bounce " (since Linux 2.6.12)" +.\" commit edfbe2b0038723e5699ab22695ccd62b5542a5c1 +.TP +.IR nr_vmscan_write " (since Linux 2.6.19)" +.\" commit e129b5c23c2b471d47f1c5d2b8b193fc2034af43 +.TP +.IR nr_vmscan_immediate_reclaim " (since Linux 3.2)" +.\" commit 49ea7eb65e7c5060807fb9312b1ad4c3eab82e2c +.TP +.IR nr_writeback_temp " (since Linux 2.6.26)" +.\" commit fc3ba692a4d19019387c5acaea63131f9eab05dd +.TP +.IR nr_isolated_anon " (since Linux 2.6.32)" +.\" commit a731286de62294b63d8ceb3c5914ac52cc17e690 +.TP +.IR nr_isolated_file " (since Linux 2.6.32)" +.\" commit a731286de62294b63d8ceb3c5914ac52cc17e690 +.TP +.IR nr_shmem " (since Linux 2.6.32)" +.\" commit 4b02108ac1b3354a22b0d83c684797692efdc395 +Pages used by shmem and +.BR tmpfs (5). +.TP +.IR nr_dirtied " (since Linux 2.6.37)" +.\" commit ea941f0e2a8c02ae876cd73deb4e1557248f258c +.TP +.IR nr_written " (since Linux 2.6.37)" +.\" commit ea941f0e2a8c02ae876cd73deb4e1557248f258c +.TP +.IR nr_pages_scanned " (since Linux 3.17)" +.\" commit 0d5d823ab4e608ec7b52ac4410de4cb74bbe0edd +.TP +.IR numa_hit " (since Linux 2.6.18)" +.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_NUMA . +.TP +.IR numa_miss " (since Linux 2.6.18)" +.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_NUMA . +.TP +.IR numa_foreign " (since Linux 2.6.18)" +.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_NUMA . +.TP +.IR numa_interleave " (since Linux 2.6.18)" +.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_NUMA . +.TP +.IR numa_local " (since Linux 2.6.18)" +.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_NUMA . +.TP +.IR numa_other " (since Linux 2.6.18)" +.\" commit ca889e6c45e0b112cb2ca9d35afc66297519b5d5 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_NUMA . +.TP +.IR workingset_refault " (since Linux 3.15)" +.\" commit a528910e12ec7ee203095eb1711468a66b9b60b0 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR workingset_activate " (since Linux 3.15)" +.\" commit a528910e12ec7ee203095eb1711468a66b9b60b0 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR workingset_nodereclaim " (since Linux 3.15)" +.\" commit 449dd6984d0e47643c04c807f609dd56d48d5bcc +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR nr_anon_transparent_hugepages " (since Linux 2.6.38)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR nr_free_cma " (since Linux 3.7)" +.\" commit d1ce749a0db12202b711d1aba1d29e823034648d +Number of free CMA (Contiguous Memory Allocator) pages. +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR nr_dirty_threshold " (since Linux 2.6.37)" +.\" commit 79da826aee6a10902ef411bc65864bd02102fa83 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR nr_dirty_background_threshold " (since Linux 2.6.37)" +.\" commit 79da826aee6a10902ef411bc65864bd02102fa83 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgpgin " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgpgout " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pswpin " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pswpout " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgalloc_dma " (since Linux 2.6.5)" +.\" Linux 2.6.0 had pgalloc +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgalloc_dma32 " (since Linux 2.6.16)" +.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgalloc_normal " (since Linux 2.6.5)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgalloc_high " (since Linux 2.6.5)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HIGHMEM . +.TP +.IR pgalloc_movable " (since Linux 2.6.23)" +.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgfree " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgactivate " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgdeactivate " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgfault " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgmajfault " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgrefill_dma " (since Linux 2.6.5)" +.\" Linux 2.6.0 had pgrefill +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgrefill_dma32 " (since Linux 2.6.16)" +.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgrefill_normal " (since Linux 2.6.5)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgrefill_high " (since Linux 2.6.5)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HIGHMEM . +.TP +.IR pgrefill_movable " (since Linux 2.6.23)" +.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.\" Formerly there were +.\" pgsteal_high +.\" pgsteal_normal +.\" pgsteal_dma32 +.\" pgsteal_dma +.\" These were split out into pgsteal_kswapd* and pgsteal_direct* +.\" in commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.TP +.IR pgsteal_kswapd_dma " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" Linux 2.6.0 had pgsteal +.\" Present only if the kernel was configured with +.\" .\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgsteal_kswapd_dma32 " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgsteal_kswapd_normal " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgsteal_kswapd_high " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HIGHMEM . +.TP +.IR pgsteal_kswapd_movable " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.I pgsteal_direct_dma +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgsteal_direct_dma32 " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgsteal_direct_normal " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgsteal_direct_high " (since Linux 3.4)" +.\" commit 904249aa68010c8e223263c922fcbb840a3f42e4 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HIGHMEM . +.TP +.IR pgsteal_direct_movable " (since Linux 2.6.23)" +.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.I pgscan_kswapd_dma +.\" Linux 2.6.0 had pgscan +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgscan_kswapd_dma32 " (since Linux 2.6.16)" +.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgscan_kswapd_normal " (since Linux 2.6.5)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.I pgscan_kswapd_high +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HIGHMEM . +.TP +.IR pgscan_kswapd_movable " (since Linux 2.6.23)" +.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.I pgscan_direct_dma +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgscan_direct_dma32 " (since Linux 2.6.16)" +.\" commit 9328b8faae922e52073785ed6c1eaa8565648a0e +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.I pgscan_direct_normal +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.I pgscan_direct_high +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HIGHMEM . +.TP +.IR pgscan_direct_movable " (since Linux 2.6.23)" +.\" commit 2a1e274acf0b1c192face19a4be7c12d4503eaaf +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgscan_direct_throttle " (since Linux 3.6)" +.\" commit 68243e76ee343d63c6cf76978588a885951e2818 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR zone_reclaim_failed " (since linux 2.6.31)" +.\" commit 24cf72518c79cdcda486ed26074ff8151291cf65 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_NUMA . +.TP +.IR pginodesteal " (since linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR slabs_scanned " (since linux 2.6.5)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR kswapd_inodesteal " (since linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR kswapd_low_wmark_hit_quickly " (since Linux 2.6.33)" +.\" commit bb3ab596832b920c703d1aea1ce76d69c0f71fb7 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR kswapd_high_wmark_hit_quickly " (since Linux 2.6.33)" +.\" commit bb3ab596832b920c703d1aea1ce76d69c0f71fb7 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pageoutrun " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR allocstall " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR pgrotated " (since Linux 2.6.0)" +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR drop_pagecache " (since Linux 3.15)" +.\" commit 5509a5d27b971a90b940e148ca9ca53312e4fa7a +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR drop_slab " (since Linux 3.15)" +.\" commit 5509a5d27b971a90b940e148ca9ca53312e4fa7a +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR numa_pte_updates " (since Linux 3.8)" +.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_NUMA_BALANCING . +.TP +.IR numa_huge_pte_updates " (since Linux 3.13)" +.\" commit 72403b4a0fbdf433c1fe0127e49864658f6f6468 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_NUMA_BALANCING . +.TP +.IR numa_hint_faults " (since Linux 3.8)" +.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_NUMA_BALANCING . +.TP +.IR numa_hint_faults_local " (since Linux 3.8)" +.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_NUMA_BALANCING . +.TP +.IR numa_pages_migrated " (since Linux 3.8)" +.\" commit 03c5a6e16322c997bf8f264851bfa3f532ad515f +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_NUMA_BALANCING +.\" and +.\" .BR CONFIG_NUMA_BALANCING . +.TP +.IR pgmigrate_success " (since Linux 3.8)" +.\" commit 5647bc293ab15f66a7b1cda850c5e9d162a6c7c2 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_MIGRATION . +.TP +.IR pgmigrate_fail " (since Linux 3.8)" +.\" commit 5647bc293ab15f66a7b1cda850c5e9d162a6c7c2 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_MIGRATION . +.TP +.IR compact_migrate_scanned " (since Linux 3.8)" +.\" commit 397487db696cae0b026a474a5cd66f4e372995e6 +.\" Linux 3.8 dropped compact_blocks_moved, compact_pages_moved, and +.\" compact_pagemigrate_failed +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_COMPACTION . +.TP +.IR compact_free_scanned " (since Linux 3.8)" +.\" commit 397487db696cae0b026a474a5cd66f4e372995e6 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_COMPACTION . +.TP +.IR compact_isolated " (since Linux 3.8)" +.\" commit 397487db696cae0b026a474a5cd66f4e372995e6 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_COMPACTION . +.TP +.IR compact_stall " (since Linux 2.6.35)" +.\" commit 56de7263fcf3eb10c8dcdf8d59a9cec831795f3f +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_COMPACTION . +.TP +.IR compact_fail " (since Linux 2.6.35)" +.\" commit 56de7263fcf3eb10c8dcdf8d59a9cec831795f3f +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_COMPACTION . +.TP +.IR compact_success " (since Linux 2.6.35)" +.\" commit 56de7263fcf3eb10c8dcdf8d59a9cec831795f3f +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_COMPACTION . +.TP +.IR htlb_buddy_alloc_success " (since Linux 2.6.26)" +.\" commit 3b1163006332302117b1b2acf226d4014ff46525 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HUGETLB_PAGE . +.TP +.IR htlb_buddy_alloc_fail " (since Linux 2.6.26)" +.\" commit 3b1163006332302117b1b2acf226d4014ff46525 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_HUGETLB_PAGE . +.TP +.IR unevictable_pgs_culled " (since Linux 2.6.28)" +.\" commit bbfd28eee9fbd73e780b19beb3dc562befbb94fa +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR unevictable_pgs_scanned " (since Linux 2.6.28)" +.\" commit bbfd28eee9fbd73e780b19beb3dc562befbb94fa +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR unevictable_pgs_rescued " (since Linux 2.6.28)" +.\" commit bbfd28eee9fbd73e780b19beb3dc562befbb94fa +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR unevictable_pgs_mlocked " (since Linux 2.6.28)" +.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR unevictable_pgs_munlocked " (since Linux 2.6.28)" +.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR unevictable_pgs_cleared " (since Linux 2.6.28)" +.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.TP +.IR unevictable_pgs_stranded " (since Linux 2.6.28)" +.\" commit 5344b7e648980cc2ca613ec03a56a8222ff48820 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS . +.\" Linux 3.7 removed unevictable_pgs_mlockfreed +.TP +.IR thp_fault_alloc " (since Linux 2.6.39)" +.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145 +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_TRANSPARENT_HUGEPAGE . +.TP +.IR thp_fault_fallback " (since Linux 2.6.39)" +.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145 +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_TRANSPARENT_HUGEPAGE . +.TP +.IR thp_collapse_alloc " (since Linux 2.6.39)" +.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145 +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_TRANSPARENT_HUGEPAGE . +.TP +.IR thp_collapse_alloc_failed " (since Linux 2.6.39)" +.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145 +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_TRANSPARENT_HUGEPAGE . +.TP +.IR thp_split " (since Linux 2.6.39)" +.\" commit 81ab4201fb7d91d6b0cd9ad5b4b16776e4bed145 +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_TRANSPARENT_HUGEPAGE . +.TP +.IR thp_zero_page_alloc " (since Linux 3.8)" +.\" commit d8a8e1f0da3d29d7268b3300c96a059d63901b76 +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_TRANSPARENT_HUGEPAGE . +.TP +.IR thp_zero_page_alloc_failed " (since Linux 3.8)" +.\" commit d8a8e1f0da3d29d7268b3300c96a059d63901b76 +See the kernel source file +.IR Documentation/admin\-guide/mm/transhuge.rst . +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_TRANSPARENT_HUGEPAGE . +.TP +.IR balloon_inflate " (since Linux 3.18)" +.\" commit 09316c09dde33aae14f34489d9e3d243ec0d5938 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_MEMORY_BALLOON . +.TP +.IR balloon_deflate " (since Linux 3.18)" +.\" commit 09316c09dde33aae14f34489d9e3d243ec0d5938 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS +.\" and +.\" .BR CONFIG_MEMORY_BALLOON . +.TP +.IR balloon_migrate " (since Linux 3.18)" +.\" commit 09316c09dde33aae14f34489d9e3d243ec0d5938 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_VM_EVENT_COUNTERS , +.\" .BR CONFIG_MEMORY_BALLOON , +.\" and +.\" .BR CONFIG_BALLOON_COMPACTION . +.TP +.IR nr_tlb_remote_flush " (since Linux 3.12)" +.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_DEBUG_TLBFLUSH +.\" and +.\" .BR CONFIG_SMP . +.TP +.IR nr_tlb_remote_flush_received " (since Linux 3.12)" +.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_DEBUG_TLBFLUSH +.\" and +.\" .BR CONFIG_SMP . +.TP +.IR nr_tlb_local_flush_all " (since Linux 3.12)" +.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_DEBUG_TLBFLUSH . +.TP +.IR nr_tlb_local_flush_one " (since Linux 3.12)" +.\" commit 9824cf9753ecbe8f5b47aa9b2f218207defea211 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_DEBUG_TLBFLUSH . +.TP +.IR vmacache_find_calls " (since Linux 3.16)" +.\" commit 4f115147ff802267d0aa41e361c5aa5bd933d896 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_DEBUG_VM_VMACACHE . +.TP +.IR vmacache_find_hits " (since Linux 3.16)" +.\" commit 4f115147ff802267d0aa41e361c5aa5bd933d896 +.\" Present only if the kernel was configured with +.\" .BR CONFIG_DEBUG_VM_VMACACHE . +.TP +.IR vmacache_full_flushes " (since Linux 3.19)" +.\" commit f5f302e21257ebb0c074bbafc37606c26d28cc3d +.\" Present only if the kernel was configured with +.\" .BR CONFIG_DEBUG_VM_VMACACHE . +.RE +.TP +.IR /proc/zoneinfo " (since Linux 2.6.13)" +This file displays information about memory zones. +This is useful for analyzing virtual memory behavior. +.\" FIXME more should be said about /proc/zoneinfo +.SH NOTES +Many files contain strings (e.g., the environment and command line) +that are in the internal format, +with subfields terminated by null bytes (\[aq]\e0\[aq]). +When inspecting such files, you may find that the results are more readable +if you use a command of the following form to display them: +.PP +.in +4n +.EX +.RB "$" " cat \fIfile\fP | tr \[aq]\e000\[aq] \[aq]\en\[aq]" +.EE +.in +.PP +This manual page is incomplete, possibly inaccurate, and is the kind +of thing that needs to be updated very often. +.\" .SH ACKNOWLEDGEMENTS +.\" The material on /proc/sys/fs and /proc/sys/kernel is closely based on +.\" kernel source documentation files written by Rik van Riel. +.SH SEE ALSO +.BR cat (1), +.BR dmesg (1), +.BR find (1), +.BR free (1), +.BR htop (1), +.BR init (1), +.BR ps (1), +.BR pstree (1), +.BR tr (1), +.BR uptime (1), +.BR chroot (2), +.BR mmap (2), +.BR readlink (2), +.BR syslog (2), +.BR slabinfo (5), +.BR sysfs (5), +.BR hier (7), +.BR namespaces (7), +.BR time (7), +.BR arp (8), +.BR hdparm (8), +.BR ifconfig (8), +.BR lsmod (8), +.BR lspci (8), +.BR mount (8), +.BR netstat (8), +.BR procinfo (8), +.BR route (8), +.BR sysctl (8) +.PP +The Linux kernel source files: +.IR Documentation/filesystems/proc.rst , +.IR Documentation/admin\-guide/sysctl/fs.rst , +.IR Documentation/admin\-guide/sysctl/kernel.rst , +.IR Documentation/admin\-guide/sysctl/net.rst , +and +.IR Documentation/admin\-guide/sysctl/vm.rst . diff --git a/man5/procfs.5 b/man5/procfs.5 new file mode 100644 index 0000000..d8be74a --- /dev/null +++ b/man5/procfs.5 @@ -0,0 +1 @@ +.so man5/proc.5 diff --git a/man5/protocols.5 b/man5/protocols.5 new file mode 100644 index 0000000..7939407 --- /dev/null +++ b/man5/protocols.5 @@ -0,0 +1,66 @@ +.\" Copyright (c) 1995 Martin Schulze <joey@infodrom.north.de> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" 1995-10-18 Martin Schulze <joey@infodrom.north.de> +.\" * first released +.\" 2002-09-22 Seth W. Klein <sk@sethwklein.net> +.\" * protocol numbers are now assigned by the IANA +.\" +.TH protocols 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +protocols \- protocols definition file +.SH DESCRIPTION +This file is a plain ASCII file, describing the various DARPA internet +protocols that are available from the TCP/IP subsystem. +It should be +consulted instead of using the numbers in the ARPA include files, or, +even worse, just guessing them. +These numbers will occur in the +protocol field of any IP header. +.PP +Keep this file untouched since changes would result in incorrect IP +packages. +Protocol numbers and names are specified by the IANA +(Internet Assigned Numbers Authority). +.\" .. by the DDN Network Information Center. +.PP +Each line is of the following format: +.PP +.RS +.I protocol number aliases ... +.RE +.PP +where the fields are delimited by spaces or tabs. +Empty lines are ignored. +If a line contains a hash mark (#), the hash mark and the part +of the line following it are ignored. +.PP +The field descriptions are: +.TP +.I protocol +the native name for the protocol. +For example +.IR ip , +.IR tcp , +or +.IR udp . +.TP +.I number +the official number for this protocol as it will appear within the IP +header. +.TP +.I aliases +optional aliases for the protocol. +.PP +This file might be distributed over a network using a network-wide +naming service like Yellow Pages/NIS or BIND/Hesiod. +.SH FILES +.TP +.I /etc/protocols +The protocols definition file. +.SH SEE ALSO +.BR getprotoent (3) +.PP +.UR http://www.iana.org\:/assignments\:/protocol\-numbers +.UE diff --git a/man5/repertoiremap.5 b/man5/repertoiremap.5 new file mode 100644 index 0000000..bf1238d --- /dev/null +++ b/man5/repertoiremap.5 @@ -0,0 +1,58 @@ +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.TH repertoiremap 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +repertoiremap \- map symbolic character names to Unicode code points +.SH DESCRIPTION +A repertoire map defines mappings between symbolic character names +(mnemonics) and Unicode code points when compiling a locale with +.BR localedef (1). +Using a repertoire map is optional, it is needed only when symbolic +names are used instead of now preferred Unicode code points. +.SS Syntax +The repertoiremap file starts with a header that may consist of the +following keywords: +.TP +.I comment_char +is followed by a character that will be used as the +comment character for the rest of the file. +It defaults to the number sign (#). +.TP +.I escape_char +is followed by a character that should be used as the escape character +for the rest of the file to mark characters that should be interpreted +in a special way. +It defaults to the backslash (\e). +.PP +The mapping section starts with the keyword +.I CHARIDS +in the first column. +.PP +The mapping lines have the following form: +.TP +.I <symbolic-name> <code-point> comment +This defines exactly one mapping, +.I comment +being optional. +.PP +The mapping section ends with the string +.IR "END CHARIDS" . +.SH FILES +.TP +.I /usr/share/i18n/repertoiremaps +Usual default repertoire map path. +.SH STANDARDS +POSIX.2. +.SH NOTES +Repertoire maps are deprecated in favor of Unicode code points. +.SH EXAMPLES +A mnemonic for the Euro sign can be defined as follows: +.PP +.nf +<Eu> <U20AC> EURO SIGN +.fi +.SH SEE ALSO +.BR locale (1), +.BR localedef (1), +.BR charmap (5), +.BR locale (5) diff --git a/man5/resolv.conf.5 b/man5/resolv.conf.5 new file mode 100644 index 0000000..1ea918d --- /dev/null +++ b/man5/resolv.conf.5 @@ -0,0 +1,406 @@ +.\" Copyright (c) 1986 The Regents of the University of California. +.\" All rights reserved. +.\" +.\" %%%LICENSE_START(PERMISSIVE_MISC) +.\" Redistribution and use in source and binary forms are permitted +.\" provided that the above copyright notice and this paragraph are +.\" duplicated in all such forms and that any documentation, +.\" advertising materials, and other materials related to such +.\" distribution and use acknowledge that the software was developed +.\" by the University of California, Berkeley. The name of the +.\" University may not be used to endorse or promote products derived +.\" from this software without specific prior written permission. +.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED +.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. +.\" %%%LICENSE_END +.\" +.\" @(#)resolver.5 5.9 (Berkeley) 12/14/89 +.\" $Id: resolver.5,v 8.6 1999/05/21 00:01:02 vixie Exp $ +.\" +.\" Added ndots remark by Bernhard R. Link - debian bug #182886 +.\" +.TH resolv.conf 5 2023-05-05 "Linux man-pages 6.05.01" +.UC 4 +.SH NAME +resolv.conf \- resolver configuration file +.SH SYNOPSIS +.nf +.B /etc/resolv.conf +.fi +.SH DESCRIPTION +The +.I resolver +is a set of routines in the C library +that provide access to the Internet Domain Name System (DNS). +The resolver configuration file contains information that is read +by the resolver routines the first time they are invoked by a process. +The file is designed to be human readable and contains a list of +keywords with values that provide various types of resolver information. +The configuration file is considered a trusted source of DNS information; +see the +.B trust-ad +option below for details. +.PP +If this file does not exist, only the name server on the local machine +will be queried, and the search list contains the local domain name +determined from the hostname. +.PP +The different configuration options are: +.TP +\fBnameserver\fP Name server IP address +Internet address of a name server that the resolver should query, +either an IPv4 address (in dot notation), +or an IPv6 address in colon (and possibly dot) notation as per RFC 2373. +Up to +.B MAXNS +(currently 3, see \fI<resolv.h>\fP) name servers may be listed, +one per keyword. +If there are multiple servers, +the resolver library queries them in the order listed. +If no \fBnameserver\fP entries are present, +the default is to use the name server on the local machine. +(The algorithm used is to try a name server, and if the query times out, +try the next, until out of name servers, +then repeat trying all the name servers +until a maximum number of retries are made.) +.TP +\fBsearch\fP Search list for host-name lookup. +By default, the search list contains one entry, the local domain name. +It is determined from the local hostname returned by +.BR gethostname (2); +the local domain name is taken to be everything after the first +\[aq].\[aq]. +Finally, if the hostname does not contain a \[aq].\[aq], the +root domain is assumed as the local domain name. +.IP +This may be changed by listing the desired domain search path +following the \fIsearch\fP keyword with spaces or tabs separating +the names. +Resolver queries having fewer than +.I ndots +dots (default is 1) in them will be attempted using each component +of the search path in turn until a match is found. +For environments with multiple subdomains please read +.BI "options ndots:" n +below to avoid man-in-the-middle attacks and unnecessary +traffic for the root-dns-servers. +.\" When having a resolv.conv with a line +.\" search subdomain.domain.tld domain.tld +.\" and doing a hostlookup, for example by +.\" ping host.anothersubdomain +.\" it sends dns-requests for +.\" host.anothersubdomain. +.\" host.anothersubdomain.subdomain.domain.tld. +.\" host.anothersubdomain.domain.tld. +.\" thus not only causing unnecessary traffic for the root-dns-servers +.\" but broadcasting information to the outside and making man-in-the-middle +.\" attacks possible. +Note that this process may be slow and will generate a lot of network +traffic if the servers for the listed domains are not local, +and that queries will time out if no server is available +for one of the domains. +.IP +If there are multiple +.B search +directives, only the search list from the last instance is used. +.IP +In glibc 2.25 and earlier, the search list is limited to six domains +with a total of 256 characters. +Since glibc 2.26, +.\" glibc commit 3f853f22c87f0b671c0366eb290919719fa56c0e +the search list is unlimited. +.IP +The +.B domain +directive is an obsolete name for the +.B search +directive that handles one search list entry only. +.TP +\fBsortlist\fP +This option allows addresses returned by +.BR gethostbyname (3) +to be sorted. +A sortlist is specified by IP-address-netmask pairs. +The netmask is +optional and defaults to the natural netmask of the net. +The IP address +and optional network pairs are separated by slashes. +Up to 10 pairs may +be specified. +Here is an example: +.IP +.in +4n +sortlist 130.155.160.0/255.255.240.0 130.155.0.0 +.in +.TP +\fBoptions\fP +Options allows certain internal resolver variables to be modified. +The syntax is +.RS +.IP +\fBoptions\fP \fIoption\fP \fI...\fP +.PP +where \fIoption\fP is one of the following: +.TP +\fBdebug\fP +.\" Since glibc 2.2? +Sets +.B RES_DEBUG +in +.I _res.options +(effective only if glibc was built with debug support; see +.BR resolver (3)). +.TP +.BI ndots: n +.\" Since glibc 2.2 +Sets a threshold for the number of dots which +must appear in a name given to +.BR res_query (3) +(see +.BR resolver (3)) +before an \fIinitial absolute query\fP will be made. +The default for +\fIn\fP is 1, meaning that if there are any dots in a name, the name +will be tried first as an absolute name before any \fIsearch list\fP +elements are appended to it. +The value for this option is silently capped to 15. +.TP +.BI timeout: n +.\" Since glibc 2.2 +Sets the amount of time the resolver will wait for a +response from a remote name server before retrying the +query via a different name server. +This may +.B not +be the total time taken by any resolver API call and there is no +guarantee that a single resolver API call maps to a single timeout. +Measured in seconds, +the default is +.B RES_TIMEOUT +(currently 5, see \fI<resolv.h>\fP). +The value for this option is silently capped to 30. +.TP +.BI attempts: n +Sets the number of times the resolver will send a +query to its name servers before giving up and returning +an error to the calling application. +The default is +.B RES_DFLRETRY +(currently 2, see \fI<resolv.h>\fP). +The value for this option is silently capped to 5. +.TP +.B rotate +.\" Since glibc 2.2 +Sets +.B RES_ROTATE +in +.IR _res.options , +which causes round-robin selection of name servers from among those listed. +This has the effect of spreading the query load among all listed servers, +rather than having all clients try the first listed server first every time. +.TP +.B no\-aaaa (since glibc 2.36) +.\" f282cdbe7f436c75864e5640a409a10485e9abb2 +Sets +.B RES_NOAAAA +in +.IR _res.options , +which suppresses AAAA queries made by the stub resolver, +including AAAA lookups triggered by NSS-based interfaces such as +.BR getaddrinfo (3). +Only DNS lookups are affected: IPv6 data in +.BR hosts (5) +is still used, +.BR getaddrinfo (3) +with +.B AI_PASSIVE +will still produce IPv6 addresses, +and configured IPv6 name servers are still used. +To produce correct Name Error (NXDOMAIN) results, +AAAA queries are translated to A queries. +This option is intended preliminary for diagnostic purposes, +to rule out that AAAA DNS queries have adverse impact. +It is incompatible with EDNS0 usage and DNSSEC validation by applications. +.TP +.B no\-check\-names +.\" since glibc 2.2 +Sets +.B RES_NOCHECKNAME +in +.IR _res.options , +which disables the modern BIND checking of incoming hostnames and +mail names for invalid characters such as underscore (_), non-ASCII, +or control characters. +.TP +.B inet6 +.\" Since glibc 2.2 +Sets +.B RES_USE_INET6 +in +.IR _res.options . +This has the effect of trying an AAAA query before an A query inside the +.BR gethostbyname (3) +function, and of mapping IPv4 responses in IPv6 "tunneled form" +if no AAAA records are found but an A record set exists. +Since glibc 2.25, +.\" b76e065991ec01299225d9da90a627ebe6c1ac97 +this option is deprecated; applications should use +.BR getaddrinfo (3), +rather than +.BR gethostbyname (3). +.TP +.BR ip6\-bytestring " (since glibc 2.3.4 to glibc 2.24)" +Sets +.B RES_USEBSTRING +in +.IR _res.options . +This causes reverse IPv6 lookups to be made using the bit-label format +described in RFC\ 2673; +if this option is not set (which is the default), then nibble format is used. +This option was removed in glibc 2.25, +since it relied on a backward-incompatible +DNS extension that was never deployed on the Internet. +.TP +.BR ip6\-dotint / no\-ip6\-dotint " (glibc 2.3.4 to glibc 2.24)" +Clear/set +.B RES_NOIP6DOTINT +in +.IR _res.options . +When this option is clear +.RB ( ip6\-dotint ), +reverse IPv6 lookups are made in the (deprecated) +.I ip6.int +zone; +when this option is set +.RB ( no\-ip6\-dotint ), +reverse IPv6 lookups are made in the +.I ip6.arpa +zone by default. +These options are available up to glibc 2.24, where +.B no\-ip6\-dotint +is the default. +Since +.B ip6\-dotint +support long ago ceased to be available on the Internet, +these options were removed in glibc 2.25. +.TP +.BR edns0 " (since glibc 2.6)" +Sets +.B RES_USE_EDNS0 +in +.IR _res.options . +This enables support for the DNS extensions described in RFC\ 2671. +.TP +.BR single\-request " (since glibc 2.10)" +Sets +.B RES_SNGLKUP +in +.IR _res.options . +By default, glibc performs IPv4 and IPv6 lookups in parallel since +glibc 2.9. +Some appliance DNS servers +cannot handle these queries properly and make the requests time out. +This option disables the behavior and makes glibc perform the IPv6 +and IPv4 requests sequentially (at the cost of some slowdown of the +resolving process). +.TP +.BR single\-request\-reopen " (since glibc 2.9)" +Sets +.B RES_SNGLKUPREOP +in +.IR _res.options . +The resolver uses the same socket for the A and AAAA requests. +Some hardware mistakenly sends back only one reply. +When that happens the client system will sit and wait for the second reply. +Turning this option on changes this behavior +so that if two requests from the same port are not handled correctly it will +close the socket and open a new one before sending the second request. +.TP +.BR no\-tld\-query " (since glibc 2.14)" +Sets +.B RES_NOTLDQUERY +in +.IR _res.options . +This option causes +.BR res_nsearch () +to not attempt to resolve an unqualified name +as if it were a top level domain (TLD). +This option can cause problems if the site has ``localhost'' as a TLD +rather than having localhost on one or more elements of the search list. +This option has no effect if neither RES_DEFNAMES or RES_DNSRCH is set. +.TP +.BR use\-vc " (since glibc 2.14)" +Sets +.B RES_USEVC +in +.IR _res.options . +This option forces the use of TCP for DNS resolutions. +.\" aef16cc8a4c670036d45590877d411a97f01e0cd +.TP +.BR no\-reload " (since glibc 2.26)" +Sets +.B RES_NORELOAD +in +.IR _res.options . +This option disables automatic reloading of a changed configuration file. +.TP +.BR trust\-ad " (since glibc 2.31)" +.\" 446997ff1433d33452b81dfa9e626b8dccf101a4 +Sets +.B RES_TRUSTAD +in +.IR _res.options . +This option controls the AD bit behavior of the stub resolver. +If a validating resolver sets the AD bit in a response, +it indicates that the data in the response was verified according +to the DNSSEC protocol. +In order to rely on the AD bit, the local system has to +trust both the DNSSEC-validating resolver and the network path to it, +which is why an explicit opt-in is required. +If the +.B trust\-ad +option is active, the stub resolver sets the AD bit in outgoing DNS +queries (to enable AD bit support), and preserves the AD bit in responses. +Without this option, the AD bit is not set in queries, +and it is always removed from responses before they are returned to the +application. +This means that applications can trust the AD bit in responses if the +.B trust\-ad +option has been set correctly. +.IP +In glibc 2.30 and earlier, +the AD is not set automatically in queries, +and is passed through unchanged to applications in responses. +.RE +.PP +The \fIsearch\fP keyword of a system's \fIresolv.conf\fP file can be +overridden on a per-process basis by setting the environment variable +.B LOCALDOMAIN +to a space-separated list of search domains. +.PP +The \fIoptions\fP keyword of a system's \fIresolv.conf\fP file can be +amended on a per-process basis by setting the environment variable +.B RES_OPTIONS +to a space-separated list of resolver options +as explained above under \fBoptions\fP. +.PP +The keyword and value must appear on a single line, and the keyword +(e.g., \fBnameserver\fP) must start the line. +The value follows the keyword, separated by white space. +.PP +Lines that contain a semicolon (;) or hash character (#) +in the first column are treated as comments. +.SH FILES +.IR /etc/resolv.conf , +.I <resolv.h> +.SH SEE ALSO +.BR gethostbyname (3), +.BR resolver (3), +.BR host.conf (5), +.BR hosts (5), +.BR nsswitch.conf (5), +.BR hostname (7), +.BR named (8) +.PP +Name Server Operations Guide for BIND diff --git a/man5/resolver.5 b/man5/resolver.5 new file mode 100644 index 0000000..86104b9 --- /dev/null +++ b/man5/resolver.5 @@ -0,0 +1 @@ +.so man5/resolv.conf.5 diff --git a/man5/rpc.5 b/man5/rpc.5 new file mode 100644 index 0000000..4f1fe2c --- /dev/null +++ b/man5/rpc.5 @@ -0,0 +1,83 @@ +.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license) +.\" +.\" %%%LICENSE_START(BSD_ONELINE_CDROM) +.\" This page was taken from the 4.4BSD-Lite CDROM (BSD license) +.\" %%%LICENSE_END +.\" +.\" @(#)rpc.5 2.2 88/08/03 4.0 RPCSRC; from 1.4 87/11/27 SMI; +.TH rpc 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +rpc \- RPC program number data base +.SH SYNOPSIS +.nf +.B /etc/rpc +.fi +.SH DESCRIPTION +The +.I rpc +file contains user readable names that +can be used in place of RPC program numbers. +Each line has the following information: +.PP +.PD 0 +.IP \[bu] 3 +name of server for the RPC program +.IP \[bu] +RPC program number +.IP \[bu] +aliases +.PD +.PP +Items are separated by any number of blanks and/or +tab characters. +A \[aq]#\[aq] indicates the beginning of a comment; characters from +the \[aq]#\[aq] to the end of the line are not interpreted by routines +which search the file. +.PP +Here is an example of the +.I /etc/rpc +file from the Sun RPC Source distribution. +.PP +.in +4n +.EX +# +# rpc 88/08/01 4.0 RPCSRC; from 1.12 88/02/07 SMI +# +portmapper 100000 portmap sunrpc +rstatd 100001 rstat rstat_svc rup perfmeter +rusersd 100002 rusers +nfs 100003 nfsprog +ypserv 100004 ypprog +mountd 100005 mount showmount +ypbind 100007 +walld 100008 rwall shutdown +yppasswdd 100009 yppasswd +etherstatd 100010 etherstat +rquotad 100011 rquotaprog quota rquota +sprayd 100012 spray +3270_mapper 100013 +rje_mapper 100014 +selection_svc 100015 selnsvc +database_svc 100016 +rexd 100017 rex +alis 100018 +sched 100019 +llockmgr 100020 +nlockmgr 100021 +x25.inr 100022 +statmon 100023 +status 100024 +bootparam 100026 +ypupdated 100028 ypupdate +keyserv 100029 keyserver +tfsd 100037 +nsed 100038 +nsemntd 100039 +.EE +.in +.SH FILES +.TP +.I /etc/rpc +RPC program number data base +.SH SEE ALSO +.BR getrpcent (3) diff --git a/man5/securetty.5 b/man5/securetty.5 new file mode 100644 index 0000000..a32db97 --- /dev/null +++ b/man5/securetty.5 @@ -0,0 +1,35 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sun Jul 25 11:06:27 1993 by Rik Faith (faith@cs.unc.edu) +.TH securetty 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +securetty \- list of terminals on which root is allowed to login +.SH DESCRIPTION +The file +.I /etc/securetty +contains the names of terminals +(one per line, without leading +.IR /dev/ ) +which are considered secure for the transmission of certain authentication +tokens. +.PP +It is used by (some versions of) +.BR login (1) +to restrict the terminals +on which root is allowed to login. +See +.BR login.defs (5) +if you use the shadow suite. +.PP +On PAM enabled systems, it is used for the same purpose by +.BR pam_securetty (8) +to restrict the terminals on which empty passwords are accepted. +.SH FILES +.I /etc/securetty +.SH SEE ALSO +.BR login (1), +.BR login.defs (5), +.BR pam_securetty (8) diff --git a/man5/services.5 b/man5/services.5 new file mode 100644 index 0000000..5003f61 --- /dev/null +++ b/man5/services.5 @@ -0,0 +1,199 @@ +.\" This manpage is Copyright (C) 1996 Austin Donnelly <and1000@cam.ac.uk>, +.\" with additional material Copyright (c) 1995 Martin Schulze +.\" <joey@infodrom.north.de> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" This manpage was made by merging two independently written manpages, +.\" one written by Martin Schulze (18 Oct 95), the other written by +.\" Austin Donnelly, (9 Jan 96). +.\" +.\" Thu Jan 11 12:14:41 1996 Austin Donnelly <and1000@cam.ac.uk> +.\" * Merged two services(5) manpages +.\" +.TH services 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +services \- Internet network services list +.SH DESCRIPTION +.B services +is a plain ASCII file providing a mapping between human-friendly textual +names for internet services, and their underlying assigned port +numbers and protocol types. +Every networking program should look into +this file to get the port number (and protocol) for its service. +The C library routines +.BR getservent (3), +.BR getservbyname (3), +.BR getservbyport (3), +.BR setservent (3), +and +.BR endservent (3) +support querying this file from programs. +.PP +Port numbers are assigned by the IANA (Internet Assigned Numbers +Authority), and their current policy is to assign both TCP and UDP +protocols when assigning a port number. +Therefore, most entries will +have two entries, even for TCP-only services. +.PP +Port numbers below 1024 (so-called "low numbered" ports) can be +bound to only by root (see +.BR bind (2), +.BR tcp (7), +and +.BR udp (7)). +This is so clients connecting to low numbered ports can trust +that the service running on the port is the standard implementation, +and not a rogue service run by a user of the machine. +Well-known port numbers specified by the IANA are normally +located in this root-only space. +.PP +The presence of an entry for a service in the +.B services +file does not necessarily mean that the service is currently running +on the machine. +See +.BR inetd.conf (5) +for the configuration of Internet services offered. +Note that not all +networking services are started by +.BR inetd (8), +and so won't appear in +.BR inetd.conf (5). +In particular, news (NNTP) and mail (SMTP) servers are often +initialized from the system boot scripts. +.PP +The location of the +.B services +file is defined by +.B _PATH_SERVICES +in +.IR <netdb.h> "." +This is usually set to +.IR /etc/services "." +.PP +Each line describes one service, and is of the form: +.IP +\f2service-name\ \ \ port\f3/\f2protocol\ \ \ \f1[\f2aliases ...\f1] +.TP +where: +.TP +.I service-name +is the friendly name the service is known by and looked up under. +It is case sensitive. +Often, the client program is named after the +.IR service-name "." +.TP +.I port +is the port number (in decimal) to use for this service. +.TP +.I protocol +is the type of protocol to be used. +This field should match an entry +in the +.BR protocols (5) +file. +Typical values include +.B tcp +and +.BR udp . +.TP +.I aliases +is an optional space or tab separated list of other names for this +service. +Again, the names are case +sensitive. +.PP +Either spaces or tabs may be used to separate the fields. +.PP +Comments are started by the hash sign (#) and continue until the end +of the line. +Blank lines are skipped. +.PP +The +.I service-name +should begin in the first column of the file, since leading spaces are +not stripped. +.I service-names +can be any printable characters excluding space and tab. +However, a conservative choice of characters should be used to minimize +compatibility problems. +For example, a\-z, 0\-9, and hyphen (\-) would seem a +sensible choice. +.PP +Lines not matching this format should not be present in the +file. +(Currently, they are silently skipped by +.BR getservent (3), +.BR getservbyname (3), +and +.BR getservbyport (3). +However, this behavior should not be relied on.) +.PP +.\" The following is not true as at glibc 2.8 (a line with a comma is +.\" ignored by getservent()); it's not clear if/when it was ever true. +.\" As a backward compatibility feature, the slash (/) between the +.\" .I port +.\" number and +.\" .I protocol +.\" name can in fact be either a slash or a comma (,). +.\" Use of the comma in +.\" modern installations is deprecated. +.\" +This file might be distributed over a network using a network-wide +naming service like Yellow Pages/NIS or BIND/Hesiod. +.PP +A sample +.B services +file might look like this: +.PP +.in +4n +.EX +netstat 15/tcp +qotd 17/tcp quote +msp 18/tcp # message send protocol +msp 18/udp # message send protocol +chargen 19/tcp ttytst source +chargen 19/udp ttytst source +ftp 21/tcp +# 22 \- unassigned +telnet 23/tcp +.EE +.in +.SH FILES +.TP +.I /etc/services +The Internet network services list +.TP +.I <netdb.h> +Definition of +.B _PATH_SERVICES +.\" .SH BUGS +.\" It's not clear when/if the following was ever true; +.\" it isn't true for glibc 2.8: +.\" There is a maximum of 35 aliases, due to the way the +.\" .BR getservent (3) +.\" code is written. +.\" +.\" It's not clear when/if the following was ever true; +.\" it isn't true for glibc 2.8: +.\" Lines longer than +.\" .B BUFSIZ +.\" (currently 1024) characters will be ignored by +.\" .BR getservent (3), +.\" .BR getservbyname (3), +.\" and +.\" .BR getservbyport (3). +.\" However, this will also cause the next line to be mis-parsed. +.SH SEE ALSO +.BR listen (2), +.BR endservent (3), +.BR getservbyname (3), +.BR getservbyport (3), +.BR getservent (3), +.BR setservent (3), +.BR inetd.conf (5), +.BR protocols (5), +.BR inetd (8) +.PP +Assigned Numbers RFC, most recently RFC\ 1700, (AKA STD0002). diff --git a/man5/shells.5 b/man5/shells.5 new file mode 100644 index 0000000..fcbbd22 --- /dev/null +++ b/man5/shells.5 @@ -0,0 +1,40 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Thu May 20 20:45:48 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sat Jul 24 17:11:07 1993 by Rik Faith (faith@cs.unc.edu) +.\" Modified Sun Nov 21 10:49:38 1993 by Michael Haardt +.\" Modified Sun Feb 26 15:09:15 1995 by Rik Faith (faith@cs.unc.edu) +.TH shells 5 2022-10-30 "Linux man-pages 6.05.01" +.SH NAME +shells \- pathnames of valid login shells +.SH DESCRIPTION +.I /etc/shells +is a text file which contains the full pathnames of valid login shells. +This file is consulted by +.BR chsh (1) +and available to be queried by other programs. +.PP +Be aware that there are programs which consult this file to +find out if a user is a normal user; +for example, +FTP daemons traditionally +disallow access to users with shells not included in this file. +.SH FILES +.I /etc/shells +.SH EXAMPLES +.I /etc/shells +may contain the following paths: +.PP +.in +4n +.EX +.I /bin/sh +.I /bin/bash +.I /bin/csh +.EE +.in +.SH SEE ALSO +.BR chsh (1), +.BR getusershell (3), +.BR pam_shells (8) diff --git a/man5/slabinfo.5 b/man5/slabinfo.5 new file mode 100644 index 0000000..e27ff80 --- /dev/null +++ b/man5/slabinfo.5 @@ -0,0 +1,220 @@ +.\" Copyright (c) 2001 Andreas Dilger (adilger@turbolinux.com) +.\" and Copyright (c) 2017 Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH slabinfo 5 2023-02-05 "Linux man-pages 6.05.01" +.SH NAME +slabinfo \- kernel slab allocator statistics +.SH SYNOPSIS +.nf +.B cat /proc/slabinfo +.fi +.SH DESCRIPTION +Frequently used objects in the Linux kernel +(buffer heads, inodes, dentries, etc.) +have their own cache. +The file +.I /proc/slabinfo +gives statistics on these caches. +The following (edited) output shows an example of the +contents of this file: +.PP +.EX +$ \fBsudo cat /proc/slabinfo\fP +slabinfo \- version: 2.1 +# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> ... +sigqueue 100 100 160 25 1 : tunables 0 0 0 : slabdata 4 4 0 +sighand_cache 355 405 2112 15 8 : tunables 0 0 0 : slabdata 27 27 0 +kmalloc\-8192 96 96 8192 4 8 : tunables 0 0 0 : slabdata 24 24 0 +\&... +.EE +.PP +The first line of output includes a version number, +which allows an application that is reading the file to handle changes +in the file format. +(See VERSIONS, below.) +The next line lists the names of the columns in the remaining lines. +.PP +Each of the remaining lines displays information about a specified cache. +Following the cache name, +the output shown in each line shows three components for each cache: +.IP \[bu] 3 +statistics +.IP \[bu] +tunables +.IP \[bu] +slabdata +.PP +The statistics are as follows: +.TP +.I active_objs +The number of objects that are currently active (i.e., in use). +.TP +.I num_objs +The total number of allocated objects +(i.e., objects that are both in use and not in use). +.TP +.I objsize +The size of objects in this slab, in bytes. +.TP +.I objperslab +The number of objects stored in each slab. +.TP +.I pagesperslab +The number of pages allocated for each slab. +.PP +The +.I tunables +entries in each line show tunable parameters for the corresponding cache. +When using the default SLUB allocator, there are no tunables, the +.I /proc/slabinfo +file is not writable, and the value 0 is shown in these fields. +When using the older SLAB allocator, +the tunables for a particular cache can be set by writing +lines of the following form to +.IR /proc/slabinfo : +.PP +.in +4n +.EX +# \fBecho \[aq]name limit batchcount sharedfactor\[aq] > /proc/slabinfo\fP +.EE +.in +.PP +Here, +.I name +is the cache name, and +.IR limit , +.IR batchcount , +and +.I sharedfactor +are integers defining new values for the corresponding tunables. +The +.I limit +value should be a positive value, +.I batchcount +should be a positive value that is less than or equal to +.IR limit , +and +.I sharedfactor +should be nonnegative. +If any of the specified values is invalid, +the cache settings are left unchanged. +.PP +The +.I tunables +entries in each line contain the following fields: +.TP +.I limit +The maximum number of objects that will be cached. +.\" https://lwn.net/Articles/56360/ +.\" This is the limit on the number of free objects that can be stored +.\" in the per-CPU free list for this slab cache. +.TP +.I batchcount +On SMP systems, this specifies the number of objects to transfer at one time +when refilling the available object list. +.\" https://lwn.net/Articles/56360/ +.\" On SMP systems, when we refill the available object list, instead +.\" of doing one object at a time, we do batch-count objects at a time. +.TP +.I sharedfactor +[To be documented] +.\" +.PP +The +.I slabdata +entries in each line contain the following fields: +.TP +.I active_slabs +The number of active slabs. +.TP +.I nums_slabs +The total number of slabs. +.TP +.I sharedavail +[To be documented] +.PP +Note that because of object alignment and slab cache overhead, +objects are not normally packed tightly into pages. +Pages with even one in-use object are considered in-use and cannot be +freed. +.PP +Kernels configured with +.B CONFIG_DEBUG_SLAB +will also have additional statistics fields in each line, +and the first line of the file will contain the string "(statistics)". +The statistics field include : the high water mark of active +objects; the number of times objects have been allocated; +the number of times the cache has grown (new pages added +to this cache); the number of times the cache has been +reaped (unused pages removed from this cache); and the +number of times there was an error allocating new pages +to this cache. +.\" +.\" SMP systems will also have "(SMP)" in the first line of +.\" output, and will have two additional columns for each slab, +.\" reporting the slab allocation policy for the CPU-local +.\" cache (to reduce the need for inter-CPU synchronization +.\" when allocating objects from the cache). +.\" The first column is the per-CPU limit: the maximum number of objects that +.\" will be cached for each CPU. +.\" The second column is the +.\" batchcount: the maximum number of free objects in the +.\" global cache that will be transferred to the per-CPU cache +.\" if it is empty, or the number of objects to be returned +.\" to the global cache if the per-CPU cache is full. +.\" +.\" If both slab cache statistics and SMP are defined, there +.\" will be four additional columns, reporting the per-CPU +.\" cache statistics. +.\" The first two are the per-CPU cache +.\" allocation hit and miss counts: the number of times an +.\" object was or was not available in the per-CPU cache +.\" for allocation. +.\" The next two are the per-CPU cache free +.\" hit and miss counts: the number of times a freed object +.\" could or could not fit within the per-CPU cache limit, +.\" before flushing objects to the global cache. +.SH VERSIONS +The +.I /proc/slabinfo +file first appeared in Linux 2.1.23. +The file is versioned, +and over time there have been a number of versions with different layouts: +.TP +1.0 +Present throughout the Linux 2.2.x kernel series. +.TP +1.1 +Present in the Linux 2.4.x kernel series. +.\" First appeared in Linux 2.4.0-test3 +.TP +1.2 +A format that was briefly present in the Linux 2.5 development series. +.\" from Linux 2.5.45 to Linux 2.5.70 +.TP +2.0 +Present in Linux 2.6.x kernels up to and including Linux 2.6.9. +.\" First appeared in Linux 2.5.71 +.TP +2.1 +The current format, which first appeared in Linux 2.6.10. +.SH NOTES +Only root can read and (if the kernel was configured with +.BR CONFIG_SLAB ) +write the +.I /proc/slabinfo +file. +.PP +The total amount of memory allocated to the SLAB/SLUB cache is shown in the +.I Slab +field of +.IR /proc/meminfo . +.SH SEE ALSO +.BR slabtop (1) +.PP +The kernel source file +.I Documentation/vm/slub.txt +and +.IR tools/vm/slabinfo.c . diff --git a/man5/sysfs.5 b/man5/sysfs.5 new file mode 100644 index 0000000..2edd582 --- /dev/null +++ b/man5/sysfs.5 @@ -0,0 +1,275 @@ +.\" Copyright (c) 2017 by Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH sysfs 5 2023-03-30 "Linux man-pages 6.05.01" +.SH NAME +sysfs \- a filesystem for exporting kernel objects +.SH DESCRIPTION +The +.B sysfs +filesystem is a pseudo-filesystem which provides an interface to +kernel data structures. +(More precisely, the files and directories in +.B sysfs +provide a view of the +.I kobject +structures defined internally within the kernel.) +The files under +.B sysfs +provide information about devices, kernel modules, filesystems, +and other kernel components. +.PP +The +.B sysfs +filesystem is commonly mounted at +.IR /sys . +Typically, it is mounted automatically by the system, +but it can also be mounted manually using a command such as: +.PP +.in +4n +.EX +mount \-t sysfs sysfs /sys +.EE +.in +.PP +Many of the files in the +.B sysfs +filesystem are read-only, +but some files are writable, allowing kernel variables to be changed. +To avoid redundancy, +symbolic links are heavily used to connect entries across the filesystem tree. +.\" +.SS Files and directories +The following list describes some of the files and directories under the +.I /sys +hierarchy. +.TP +.I /sys/block +This subdirectory contains one symbolic link for each block device +that has been discovered on the system. +The symbolic links point to corresponding directories under +.IR /sys/devices . +.TP +.I /sys/bus +This directory contains one subdirectory for each of the bus types +in the kernel. +Inside each of these directories are two subdirectories: +.RS +.TP +.I devices +This subdirectory contains symbolic links to entries in +.I /sys/devices +that correspond to the devices discovered on this bus. +.TP +.I drivers +This subdirectory contains one subdirectory for each device driver +that is loaded on this bus. +.RE +.TP +.I /sys/class +This subdirectory contains a single layer of further subdirectories +for each of the device classes that have been registered on the system +(e.g., terminals, network devices, block devices, graphics devices, +sound devices, and so on). +Inside each of these subdirectories are symbolic links for each of the +devices in this class. +These symbolic links refer to entries in the +.I /sys/devices +directory. +.TP +.I /sys/class/net +Each of the entries in this directory is a symbolic link +representing one of the real or virtual networking devices +that are visible in the network namespace of the process +that is accessing the directory. +Each of these symbolic links refers to entries in the +.I /sys/devices +directory. +.TP +.I /sys/dev +This directory contains two subdirectories +.I block/ +and +.IR char/ , +corresponding, respectively, +to the block and character devices on the system. +Inside each of these subdirectories are symbolic links with names of the form +.IR major-ID : minor-ID , +where the ID values correspond to the major and minor ID of a specific device. +Each symbolic link points to the +.B sysfs +directory for a device. +The symbolic links inside +.I /sys/dev +thus provide an easy way to look up the +.B sysfs +interface using the device IDs returned by a call to +.BR stat (2) +(or similar). +.IP +The following shell session shows an example from +.IR /sys/dev : +.IP +.in +4n +.EX +$ \fBstat \-c "%t %T" /dev/null\fP +1 3 +$ \fBreadlink /sys/dev/char/1\e:3\fP +\&../../devices/virtual/mem/null +$ \fBls \-Fd /sys/devices/virtual/mem/null\fP +/sys/devices/virtual/mem/null/ +$ \fBls \-d1 /sys/devices/virtual/mem/null/*\fP +/sys/devices/virtual/mem/null/dev +/sys/devices/virtual/mem/null/power/ +/sys/devices/virtual/mem/null/subsystem@ +/sys/devices/virtual/mem/null/uevent +.EE +.in +.TP +.I /sys/devices +This is a directory that contains a filesystem representation of +the kernel device tree, +which is a hierarchy of +.I device +structures within the kernel. +.TP +.I /sys/firmware +This subdirectory contains interfaces for viewing and manipulating +firmware-specific objects and attributes. +.TP +.I /sys/fs +This directory contains subdirectories for some filesystems. +A filesystem will have a subdirectory here only if it chose +to explicitly create the subdirectory. +.TP +.I /sys/fs/cgroup +This directory conventionally is used as a mount point for a +.BR tmpfs (5) +filesystem containing mount points for +.BR cgroups (7) +filesystems. +.TP +.I /sys/fs/smackfs +The directory contains configuration files for the SMACK LSM. +See the kernel source file +.IR Documentation/admin\-guide/LSM/Smack.rst . +.TP +.I /sys/hypervisor +[To be documented] +.TP +.I /sys/kernel +This subdirectory contains various files and subdirectories that provide +information about the running kernel. +.TP +.I /sys/kernel/cgroup/ +For information about the files in this directory, see +.BR cgroups (7). +.TP +.I /sys/kernel/debug/tracing +Mount point for the +.I tracefs +filesystem used by the kernel's +.I ftrace +facility. +(For information on +.IR ftrace , +see the kernel source file +.IR Documentation/trace/ftrace.txt .) +.TP +.I /sys/kernel/mm +This subdirectory contains various files and subdirectories that provide +information about the kernel's memory management subsystem. +.TP +.I /sys/kernel/mm/hugepages +This subdirectory contains one subdirectory for each of the +huge page sizes that the system supports. +The subdirectory name indicates the huge page size (e.g., +.IR hugepages\-2048kB ). +Within each of these subdirectories is a set of files +that can be used to view and (in some cases) change settings +associated with that huge page size. +For further information, see the kernel source file +.IR Documentation/admin\-guide/mm/hugetlbpage.rst . +.TP +.I /sys/module +This subdirectory contains one subdirectory +for each module that is loaded into the kernel. +The name of each directory is the name of the module. +In each of the subdirectories, there may be following files: +.RS +.TP +.I coresize +[to be documented] +.TP +.I initsize +[to be documented] +.TP +.I initstate +[to be documented] +.TP +.I refcnt +[to be documented] +.TP +.I srcversion +[to be documented] +.TP +.I taint +[to be documented] +.TP +.I uevent +[to be documented] +.TP +.I version +[to be documented] +.RE +.IP +In each of the subdirectories, there may be following subdirectories: +.RS +.TP +.I drivers +[To be documented] +.TP +.I holders +[To be documented] +.TP +.I notes +[To be documented] +.TP +.I parameters +This directory contains one file for each module parameter, +with each file containing the value of the corresponding parameter. +Some of these files are writable, allowing the +.TP +.I sections +This subdirectories contains files with information about module sections. +This information is mainly used for debugging. +.TP +.I +[To be documented] +.RE +.TP +.I /sys/power +[To be documented] +.SH STANDARDS +Linux. +.SH HISTORY +Linux 2.6.0. +.SH NOTES +This manual page is incomplete, possibly inaccurate, and is the kind +of thing that needs to be updated very often. +.SH SEE ALSO +.BR proc (5), +.BR udev (7) +.PP +P.\& Mochel. (2005). +.IR "The sysfs filesystem" . +Proceedings of the 2005 Ottawa Linux Symposium. +.\" https://www.kernel.org/pub/linux/kernel/people/mochel/doc/papers/ols-2005/mochel.pdf +.PP +The kernel source file +.I Documentation/filesystems/sysfs.txt +and various other files in +.I Documentation/ABI +and +.I Documentation/*/sysfs.txt diff --git a/man5/termcap.5 b/man5/termcap.5 new file mode 100644 index 0000000..880c957 --- /dev/null +++ b/man5/termcap.5 @@ -0,0 +1,466 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified formatting Sat Jul 24 17:13:38 1993, Rik Faith (faith@cs.unc.edu) +.\" Modified (extensions and corrections) +.\" Sun May 1 14:21:25 MET DST 1994 Michael Haardt +.\" If mistakes in the capabilities are found, please send a bug report to: +.\" michael@moria.de +.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond (esr@thyrsus.com) +.TH termcap 5 2023-03-08 "Linux man-pages 6.05.01" +.SH NAME +termcap \- terminal capability database +.SH DESCRIPTION +The termcap database is an obsolete facility for describing the +capabilities of character-cell terminals and printers. +It is retained only for compatibility with old programs; +new programs should use the +.BR terminfo (5) +database and associated libraries. +.PP +.I /etc/termcap +is an ASCII file (the database master) that lists the capabilities of +many different types of terminals. +Programs can read termcap to find +the particular escape codes needed to control the visual attributes of +the terminal actually in use. +(Other aspects of the terminal are +handled by +.BR stty (1).) +The termcap database is indexed on the +.B TERM +environment variable. +.PP +Termcap entries must be defined on a single logical line, with \[aq]\e\[aq] +used to suppress the newline. +Fields are separated by \[aq]:\[aq]. +The first field of each entry starts at the left-hand margin, +and contains a list of names for the terminal, separated by \[aq]|\[aq]. +.PP +The first subfield may (in BSD termcap entries from 4.3BSD and +earlier) contain a short name consisting of two characters. +This short name may consist of capital or small letters. +In 4.4BSD, termcap entries this field is omitted. +.PP +The second subfield (first, in the newer 4.4BSD format) contains the +name used by the environment variable +.BR TERM . +It should be spelled in lowercase letters. +Selectable hardware capabilities should be marked +by appending a hyphen and a suffix to this name. +See below for an example. +Usual suffixes are w (more than 80 characters wide), am +(automatic margins), nam (no automatic margins), and rv (reverse video +display). +The third subfield contains a long and descriptive name for +this termcap entry. +.PP +Subsequent fields contain the terminal capabilities; any continued +capability lines must be indented one tab from the left margin. +.PP +Although there is no defined order, it is suggested to write first +boolean, then numeric, and then string capabilities, each sorted +alphabetically without looking at lower or upper spelling. +Capabilities of similar functions can be written in one line. +.PP +Example for: +.nf +.PP +Head line: vt|vt101|DEC VT 101 terminal in 80 character mode:\e +Head line: Vt|vt101-w|DEC VT 101 terminal in (wide) 132 character mode:\e +Boolean: :bs:\e +Numeric: :co#80:\e +String: :sr=\eE[H:\e +.fi +.SS Boolean capabilities +.nf +5i Printer will not echo on screen +am Automatic margins which means automatic line wrap +bs Control-H (8 dec.) performs a backspace +bw Backspace on left margin wraps to previous line and right margin +da Display retained above screen +db Display retained below screen +eo A space erases all characters at cursor position +es Escape sequences and special characters work in status line +gn Generic device +hc This is a hardcopy terminal +HC The cursor is hard to see when not on bottom line +hs Has a status line +hz Hazeltine bug, the terminal can not print tilde characters +in Terminal inserts null bytes, not spaces, to fill whitespace +km Terminal has a meta key +mi Cursor movement works in insert mode +ms Cursor movement works in standout/underline mode +NP No pad character +NR ti does not reverse te +nx No padding, must use XON/XOFF +os Terminal can overstrike +ul Terminal underlines although it can not overstrike +xb Beehive glitch, f1 sends ESCAPE, f2 sends \fB\[ha]C\fP +xn Newline/wraparound glitch +xo Terminal uses xon/xoff protocol +xs Text typed over standout text will be displayed in standout +xt Teleray glitch, destructive tabs and odd standout mode +.fi +.SS Numeric capabilities +.nf +co Number of columns +dB Delay in milliseconds for backspace on hardcopy terminals +dC Delay in milliseconds for carriage return on hardcopy terminals +dF Delay in milliseconds for form feed on hardcopy terminals +dN Delay in milliseconds for new line on hardcopy terminals +dT Delay in milliseconds for tabulator stop on hardcopy terminals +dV Delay in milliseconds for vertical tabulator stop on + hardcopy terminals +it Difference between tab positions +lh Height of soft labels +lm Lines of memory +lw Width of soft labels +li Number of lines +Nl Number of soft labels +pb Lowest baud rate which needs padding +sg Standout glitch +ug Underline glitch +vt virtual terminal number +ws Width of status line if different from screen width +.fi +.SS String capabilities +.nf +!1 shifted save key +!2 shifted suspend key +!3 shifted undo key +#1 shifted help key +#2 shifted home key +#3 shifted input key +#4 shifted cursor left key +%0 redo key +%1 help key +%2 mark key +%3 message key +%4 move key +%5 next-object key +%6 open key +%7 options key +%8 previous-object key +%9 print key +%a shifted message key +%b shifted move key +%c shifted next key +%d shifted options key +%e shifted previous key +%f shifted print key +%g shifted redo key +%h shifted replace key +%i shifted cursor right key +%j shifted resume key +&0 shifted cancel key +&1 reference key +&2 refresh key +&3 replace key +&4 restart key +&5 resume key +&6 save key +&7 suspend key +&8 undo key +&9 shifted begin key +*0 shifted find key +*1 shifted command key +*2 shifted copy key +*3 shifted create key +*4 shifted delete character +*5 shifted delete line +*6 select key +*7 shifted end key +*8 shifted clear line key +*9 shifted exit key +@0 find key +@1 begin key +@2 cancel key +@3 close key +@4 command key +@5 copy key +@6 create key +@7 end key +@8 enter/send key +@9 exit key +al Insert one line +AL Insert %1 lines +ac Pairs of block graphic characters to map alternate character set +ae End alternative character set +as Start alternative character set for block graphic characters +bc Backspace, if not \fB\[ha]H\fP +bl Audio bell +bt Move to previous tab stop +cb Clear from beginning of line to cursor +cc Dummy command character +cd Clear to end of screen +ce Clear to end of line +ch Move cursor horizontally only to column %1 +cl Clear screen and cursor home +cm Cursor move to row %1 and column %2 (on screen) +CM Move cursor to row %1 and column %2 (in memory) +cr Carriage return +cs Scroll region from line %1 to %2 +ct Clear tabs +cv Move cursor vertically only to line %1 +dc Delete one character +DC Delete %1 characters +dl Delete one line +DL Delete %1 lines +dm Begin delete mode +do Cursor down one line +DO Cursor down #1 lines +ds Disable status line +eA Enable alternate character set +ec Erase %1 characters starting at cursor +ed End delete mode +ei End insert mode +ff Formfeed character on hardcopy terminals +fs Return character to its position before going to status line +F1 The string sent by function key f11 +F2 The string sent by function key f12 +F3 The string sent by function key f13 +\&... \&... +F9 The string sent by function key f19 +FA The string sent by function key f20 +FB The string sent by function key f21 +\&... \&... +FZ The string sent by function key f45 +Fa The string sent by function key f46 +Fb The string sent by function key f47 +\&... \&... +Fr The string sent by function key f63 +hd Move cursor a half line down +ho Cursor home +hu Move cursor a half line up +i1 Initialization string 1 at login +i3 Initialization string 3 at login +is Initialization string 2 at login +ic Insert one character +IC Insert %1 characters +if Initialization file +im Begin insert mode +ip Insert pad time and needed special characters after insert +iP Initialization program +K1 upper left key on keypad +K2 center key on keypad +K3 upper right key on keypad +K4 bottom left key on keypad +K5 bottom right key on keypad +k0 Function key 0 +k1 Function key 1 +k2 Function key 2 +k3 Function key 3 +k4 Function key 4 +k5 Function key 5 +k6 Function key 6 +k7 Function key 7 +k8 Function key 8 +k9 Function key 9 +k; Function key 10 +ka Clear all tabs key +kA Insert line key +kb Backspace key +kB Back tab stop +kC Clear screen key +kd Cursor down key +kD Key for delete character under cursor +ke turn keypad off +kE Key for clear to end of line +kF Key for scrolling forward/down +kh Cursor home key +kH Cursor hown down key +kI Insert character/Insert mode key +kl Cursor left key +kL Key for delete line +kM Key for exit insert mode +kN Key for next page +kP Key for previous page +kr Cursor right key +kR Key for scrolling backward/up +ks Turn keypad on +kS Clear to end of screen key +kt Clear this tab key +kT Set tab here key +ku Cursor up key +l0 Label of zeroth function key, if not f0 +l1 Label of first function key, if not f1 +l2 Label of first function key, if not f2 +\&... \&... +la Label of tenth function key, if not f10 +le Cursor left one character +ll Move cursor to lower left corner +LE Cursor left %1 characters +LF Turn soft labels off +LO Turn soft labels on +mb Start blinking +MC Clear soft margins +md Start bold mode +me End all mode like so, us, mb, md, and mr +mh Start half bright mode +mk Dark mode (Characters invisible) +ML Set left soft margin +mm Put terminal in meta mode +mo Put terminal out of meta mode +mp Turn on protected attribute +mr Start reverse mode +MR Set right soft margin +nd Cursor right one character +nw Carriage return command +pc Padding character +pf Turn printer off +pk Program key %1 to send string %2 as if typed by user +pl Program key %1 to execute string %2 in local mode +pn Program soft label %1 to show string %2 +po Turn the printer on +pO Turn the printer on for %1 (<256) bytes +ps Print screen contents on printer +px Program key %1 to send string %2 to computer +r1 Reset string 1 to set terminal to sane modes +r2 Reset string 2 to set terminal to sane modes +r3 Reset string 3 to set terminal to sane modes +RA disable automatic margins +rc Restore saved cursor position +rf Reset string filename +RF Request for input from terminal +RI Cursor right %1 characters +rp Repeat character %1 for %2 times +rP Padding after character sent in replace mode +rs Reset string +RX Turn off XON/XOFF flow control +sa Set %1 %2 %3 %4 %5 %6 %7 %8 %9 attributes +SA enable automatic margins +sc Save cursor position +se End standout mode +sf Normal scroll one line +SF Normal scroll %1 lines +so Start standout mode +sr Reverse scroll +SR scroll back %1 lines +st Set tabulator stop in all rows at current column +SX Turn on XON/XOFF flow control +ta move to next hardware tab +tc Read in terminal description from another entry +te End program that uses cursor motion +ti Begin program that uses cursor motion +ts Move cursor to column %1 of status line +uc Underline character under cursor and move cursor right +ue End underlining +up Cursor up one line +UP Cursor up %1 lines +us Start underlining +vb Visible bell +ve Normal cursor visible +vi Cursor invisible +vs Standout cursor +wi Set window from line %1 to %2 and column %3 to %4 +XF XOFF character if not \fB\[ha]S\fP +.fi +.PP +There are several ways of defining the control codes for string capabilities: +.PP +Every normal character represents itself, +except \[aq]\[ha]\[aq], \[aq]\e\[aq], and \[aq]%\[aq]. +.PP +A \fB\[ha]x\fP means Control-x. +Control-A equals 1 decimal. +.PP +\ex means a special code. +x can be one of the following characters: +.RS +E Escape (27) +.br +n Linefeed (10) +.br +r Carriage return (13) +.br +t Tabulation (9) +.br +b Backspace (8) +.br +f Form feed (12) +.br +0 Null character. +A \exxx specifies the octal character xxx. +.RE +.TP +i +Increments parameters by one. +.TP +r +Single parameter capability +.TP ++ +Add value of next character to this parameter and do binary output +.TP +2 +Do ASCII output of this parameter with a field with of 2 +.TP +d +Do ASCII output of this parameter with a field with of 3 +.TP +% +Print a \[aq]%\[aq] +.PP +If you use binary output, +then you should avoid the null character (\[aq]\e0\[aq]) +because it terminates the string. +You should reset tabulator expansion +if a tabulator can be the binary output of a parameter. +.TP +Warning: +The above metacharacters for parameters may be wrong: they document Minix +termcap which may not be compatible with Linux termcap. +.PP +The block graphic characters can be specified by three string capabilities: +.TP +as +start the alternative charset +.TP +ae +end the alternative charset +.TP +ac +pairs of characters. +The first character is the name of the block graphic +symbol and the second characters is its definition. +.PP +The following names are available: +.PP +.nf ++ right arrow (>) +, left arrow (<) +\&. down arrow (v) +0 full square (#) +I lantern (#) +- upper arrow (\[ha]) +\&' rhombus (+) +a chess board (:) +f degree (') +g plus-minus (#) +h square (#) +j right bottom corner (+) +k right upper corner (+) +l left upper corner (+) +m left bottom corner (+) +n cross (+) +o upper horizontal line (-) +q middle horizontal line (-) +s bottom horizontal line (_) +t left tee (+) +u right tee (+) +v bottom tee (+) +w normal tee (+) +x vertical line (|) +\[ti] paragraph (???) +.fi +.PP +The values in parentheses are suggested defaults which are used by the +.I curses +library, if the capabilities are missing. +.SH SEE ALSO +.BR ncurses (3), +.BR termcap (3), +.BR terminfo (5) diff --git a/man5/tmpfs.5 b/man5/tmpfs.5 new file mode 100644 index 0000000..8e4d063 --- /dev/null +++ b/man5/tmpfs.5 @@ -0,0 +1,271 @@ +.\" Copyright (c) 2016 by Michael Kerrisk <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH tmpfs 5 2023-07-28 "Linux man-pages 6.05.01" +.SH NAME +tmpfs \- a virtual memory filesystem +.SH DESCRIPTION +The +.B tmpfs +facility allows the creation of filesystems whose contents reside +in virtual memory. +Since the files on such filesystems typically reside in RAM, +file access is extremely fast. +.PP +The filesystem is automatically created when mounting +a filesystem with the type +.B tmpfs +via a command such as the following: +.PP +.in +4n +.EX +$ sudo mount \-t tmpfs \-o size=10M tmpfs /mnt/mytmpfs +.EE +.in +.PP +A +.B tmpfs +filesystem has the following properties: +.IP \[bu] 3 +The filesystem can employ swap space when physical memory pressure +demands it. +.IP \[bu] +The filesystem consumes only as much physical memory and swap space +as is required to store the current contents of the filesystem. +.IP \[bu] +During a remount operation +.RI ( "mount\ \-o\ remount" ), +the filesystem size can be changed +(without losing the existing contents of the filesystem). +.PP +If a +.B tmpfs +filesystem is unmounted, its contents are discarded (lost). +.\" See mm/shmem.c:shmem_parse_options for options it supports. +.SS Mount options +The +.B tmpfs +filesystem supports the following mount options: +.TP +.BR size "=\fIbytes\fP" +Specify an upper limit on the size of the filesystem. +The size is given in bytes, and rounded up to entire pages. +.IP +The size may have a +.BR k , +.BR m , +or +.B g +suffix for Ki, Mi, Gi (binary kilo (kibi), binary mega (mebi), and binary giga +(gibi)). +.IP +The size may also have a % suffix to limit this instance to a percentage of +physical RAM. +.IP +The default, when neither +.B size +nor +.B nr_blocks +is specified, is +.IR size=50% . +.TP +.BR nr_blocks "=\fIblocks\fP" +The same as +.BR size , +but in blocks of +.BR PAGE_CACHE_SIZE . +.IP +Blocks may be specified with +.BR k , +.BR m , +or +.B g +suffixes like +.BR size , +but not a % suffix. +.TP +.BR nr_inodes "=\fIinodes\fP" +The maximum number of inodes for this instance. +The default is half of the number of your physical RAM pages, or (on a +machine with highmem) the number of lowmem RAM pages, whichever is smaller. +.IP +Inodes may be specified with +.BR k , +.BR m , +or +.B g +suffixes like +.BR size , +but not a % suffix. +.TP +.BR mode "=\fImode\fP" +Set initial permissions of the root directory. +.TP +.BR gid "=\fIgid\fP (since Linux 2.5.7)" +.\" Technically this is also in some version of Linux 2.4. +.\" commit 099445b489625b80b1d6687c9b6072dbeaca4096 +Set the initial group ID of the root directory. +.TP +.BR uid "=\fIuid\fP (since Linux 2.5.7)" +.\" Technically this is also in some version of Linux 2.4. +.\" commit 099445b489625b80b1d6687c9b6072dbeaca4096 +Set the initial user ID of the root directory. +.TP +.BR huge "=\fIhuge_option\fR (since Linux 4.7.0)" +.\" commit 5a6e75f8110c97e2a5488894d4e922187e6cb343 +Set the huge table memory allocation policy for all files in this instance (if +.B CONFIG_TRANSPARENT_HUGEPAGE +is enabled). +.IP +The +.I huge_option +value is one of the following: +.RS +.TP +.B never +Do not allocate huge pages. +This is the default. +.TP +.B always +Attempt to allocate huge pages every time a new page is needed. +.TP +.B within_size +Only allocate huge page if it will be fully within +.IR i_size . +Also respect +.BR fadvise (2) +and +.BR madvise (2) +hints +.TP +.B advise +Only allocate huge pages if requested with +.BR fadvise (2) +or +.BR madvise (2). +.TP +.B deny +For use in emergencies, to force the huge option off from all mounts. +.TP +.B force +Force the huge option on for all mounts; useful for testing. +.RE +.TP +.BR mpol "=\fImpol_option\fR (since Linux 2.6.15)" +.\" commit 7339ff8302fd70aabf5f1ae26e0c4905fa74a495 +Set the NUMA memory allocation policy for all files in this instance (if +.B CONFIG_NUMA +is enabled). +.IP +The +.I mpol_option +value is one of the following: +.RS +.TP +.B default +Use the process allocation policy (see +.BR set_mempolicy (2)). +.TP +.BR prefer ":\fInode\fP" +Preferably allocate memory from the given +.IR node . +.TP +.BR bind ":\fInodelist\fP" +Allocate memory only from nodes in +.IR nodelist . +.TP +.B interleave +Allocate from each node in turn. +.TP +.BR interleave ":\fInodelist\fP" +Allocate from each node of +.I in +turn. +.TP +.B local +Preferably allocate memory from the local node. +.RE +.IP +In the above, +.I nodelist +is a comma-separated list of decimal numbers and ranges +that specify NUMA nodes. +A range is a pair of hyphen-separated decimal numbers, +the smallest and largest node numbers in the range. +For example, +.IR mpol=bind:0\-3,5,7,9\-15 . +.SH VERSIONS +The +.B tmpfs +facility was added in Linux 2.4, as a successor to the older +.B ramfs +facility, which did not provide limit checking or +allow for the use of swap space. +.SH NOTES +In order for user-space tools and applications to create +.B tmpfs +filesystems, the kernel must be configured with the +.B CONFIG_TMPFS +option. +.PP +The +.B tmpfs +filesystem supports extended attributes (see +.BR xattr (7)), +but +.I user +extended attributes are not permitted. +.PP +An internal shared memory filesystem is used for +System V shared memory +.RB ( shmget (2)) +and shared anonymous mappings +.RB ( mmap (2) +with the +.B MAP_SHARED +and +.B MAP_ANONYMOUS +flags). +This filesystem is available regardless of whether +the kernel was configured with the +.B CONFIG_TMPFS +option. +.PP +A +.B tmpfs +filesystem mounted at +.I /dev/shm +is used for the implementation of POSIX shared memory +.RB ( shm_overview (7)) +and POSIX semaphores +.RB ( sem_overview (7)). +.PP +The amount of memory consumed by all +.B tmpfs +filesystems is shown in the +.I Shmem +field of +.I /proc/meminfo +and in the +.I shared +field displayed by +.BR free (1). +.PP +The +.B tmpfs +facility was formerly called +.BR shmfs . +.SH SEE ALSO +.BR df (1), +.BR du (1), +.BR memfd_create (2), +.BR mmap (2), +.BR set_mempolicy (2), +.BR shm_open (3), +.BR mount (8) +.PP +The kernel source files +.I Documentation/filesystems/tmpfs.txt +and +.IR Documentation/admin\-guide/mm/transhuge.rst . diff --git a/man5/ttytype.5 b/man5/ttytype.5 new file mode 100644 index 0000000..94030e8 --- /dev/null +++ b/man5/ttytype.5 @@ -0,0 +1,56 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@moria.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified Sat Jul 24 17:17:50 1993 by Rik Faith <faith@cs.unc.edu> +.\" Modified Thu Oct 19 21:25:21 MET 1995 by Martin Schulze <joey@infodrom.north.de> +.\" Modified Mon Oct 21 17:47:19 EDT 1996 by Eric S. Raymond +.\" <esr@thyrsus.com>xk +.TH ttytype 5 2023-01-22 "Linux man-pages 6.05.01" +.SH NAME +ttytype \- terminal device to default terminal type mapping +.SH DESCRIPTION +The +.I /etc/ttytype +file associates +.BR termcap (5) +and +.BR terminfo (5) +terminal type names +with tty lines. +Each line consists of a terminal type, followed by +whitespace, followed by a tty name (a device name without the +.I /dev/ +prefix). +.PP +This association is used by the program +.BR tset (1) +to set the environment variable +.B TERM +to the default terminal name for +the user's current tty. +.PP +This facility was designed for a traditional time-sharing environment +featuring character-cell terminals hardwired to a UNIX minicomputer. +It is little used on modern workstation and personal UNIX systems. +.SH FILES +.TP +.I /etc/ttytype +the tty definitions file. +.SH EXAMPLES +A typical +.I /etc/ttytype +is: +.PP +.in +4n +.EX +con80x25 tty1 +vt320 ttys0 +.EE +.in +.SH SEE ALSO +.BR termcap (5), +.BR terminfo (5), +.BR agetty (8), +.BR mingetty (8) diff --git a/man5/tzfile.5 b/man5/tzfile.5 new file mode 100644 index 0000000..59d9f6b --- /dev/null +++ b/man5/tzfile.5 @@ -0,0 +1,496 @@ +.\" This file is in the public domain, so clarified as of +.\" 1996-06-05 by Arthur David Olson. +.TH tzfile 5 "" "Time Zone Database" +.SH NAME +tzfile \- timezone information +.SH DESCRIPTION +.ie '\(lq'' .ds lq \&"\" +.el .ds lq \(lq\" +.ie '\(rq'' .ds rq \&"\" +.el .ds rq \(rq\" +.de q +\\$3\*(lq\\$1\*(rq\\$2 +.. +.ie \n(.g .ds - \f(CR-\fP +.el .ds - \- +The timezone information files used by +.BR tzset (3) +are typically found under a directory with a name like +.IR /usr/share/zoneinfo . +These files use the format described in Internet RFC 8536. +Each file is a sequence of 8-bit bytes. +In a file, a binary integer is represented by a sequence of one or +more bytes in network order (bigendian, or high-order byte first), +with all bits significant, +a signed binary integer is represented using two's complement, +and a boolean is represented by a one-byte binary integer that is +either 0 (false) or 1 (true). +The format begins with a 44-byte header containing the following fields: +.IP * 2 +The magic four-byte ASCII sequence +.q "TZif" +identifies the file as a timezone information file. +.IP * +A byte identifying the version of the file's format +(as of 2021, either an ASCII NUL, +.q "2", +.q "3", +or +.q "4" ). +.IP * +Fifteen bytes containing zeros reserved for future use. +.IP * +Six four-byte integer values, in the following order: +.RS +.TP +.B tzh_ttisutcnt +The number of UT/local indicators stored in the file. +(UT is Universal Time.) +.TP +.B tzh_ttisstdcnt +The number of standard/wall indicators stored in the file. +.TP +.B tzh_leapcnt +The number of leap seconds for which data entries are stored in the file. +.TP +.B tzh_timecnt +The number of transition times for which data entries are stored +in the file. +.TP +.B tzh_typecnt +The number of local time types for which data entries are stored +in the file (must not be zero). +.TP +.B tzh_charcnt +The number of bytes of time zone abbreviation strings +stored in the file. +.RE +.PP +The above header is followed by the following fields, whose lengths +depend on the contents of the header: +.IP * 2 +.B tzh_timecnt +four-byte signed integer values sorted in ascending order. +These values are written in network byte order. +Each is used as a transition time (as returned by +.BR time (2)) +at which the rules for computing local time change. +.IP * +.B tzh_timecnt +one-byte unsigned integer values; +each one but the last tells which of the different types of local time types +described in the file is associated with the time period +starting with the same-indexed transition time +and continuing up to but not including the next transition time. +(The last time type is present only for consistency checking with the +POSIX-style TZ string described below.) +These values serve as indices into the next field. +.IP * +.B tzh_typecnt +.B ttinfo +entries, each defined as follows: +.in +.5i +.sp +.nf +.ta .5i +\w'unsigned char\0\0'u +struct ttinfo { + int32_t tt_utoff; + unsigned char tt_isdst; + unsigned char tt_desigidx; +}; +.in -.5i +.fi +.sp +Each structure is written as a four-byte signed integer value for +.BR tt_utoff , +in network byte order, followed by a one-byte boolean for +.B tt_isdst +and a one-byte value for +.BR tt_desigidx . +In each structure, +.B tt_utoff +gives the number of seconds to be added to UT, +.B tt_isdst +tells whether +.B tm_isdst +should be set by +.BR localtime (3) +and +.B tt_desigidx +serves as an index into the array of time zone abbreviation bytes +that follow the +.B ttinfo +entries in the file; if the designated string is "\*-00", the +.B ttinfo +entry is a placeholder indicating that local time is unspecified. +The +.B tt_utoff +value is never equal to \-2**31, to let 32-bit clients negate it without +overflow. +Also, in realistic applications +.B tt_utoff +is in the range [\-89999, 93599] (i.e., more than \-25 hours and less +than 26 hours); this allows easy support by implementations that +already support the POSIX-required range [\-24:59:59, 25:59:59]. +.IP * +.B tzh_charcnt +bytes that represent time zone designations, +which are null-terminated byte strings, each indexed by the +.B tt_desigidx +values mentioned above. +The byte strings can overlap if one is a suffix of the other. +The encoding of these strings is not specified. +.IP * +.B tzh_leapcnt +pairs of four-byte values, written in network byte order; +the first value of each pair gives the nonnegative time +(as returned by +.BR time (2)) +at which a leap second occurs or at which the leap second table expires; +the second is a signed integer specifying the correction, which is the +.I total +number of leap seconds to be applied during the time period +starting at the given time. +The pairs of values are sorted in strictly ascending order by time. +Each pair denotes one leap second, either positive or negative, +except that if the last pair has the same correction as the previous one, +the last pair denotes the leap second table's expiration time. +Each leap second is at the end of a UTC calendar month. +The first leap second has a nonnegative occurrence time, +and is a positive leap second if and only if its correction is positive; +the correction for each leap second after the first differs +from the previous leap second by either 1 for a positive leap second, +or \-1 for a negative leap second. +If the leap second table is empty, the leap-second correction is zero +for all timestamps; +otherwise, for timestamps before the first occurrence time, +the leap-second correction is zero if the first pair's correction is 1 or \-1, +and is unspecified otherwise (which can happen only in files +truncated at the start). +.IP * +.B tzh_ttisstdcnt +standard/wall indicators, each stored as a one-byte boolean; +they tell whether the transition times associated with local time types +were specified as standard time or local (wall clock) time. +.IP * +.B tzh_ttisutcnt +UT/local indicators, each stored as a one-byte boolean; +they tell whether the transition times associated with local time types +were specified as UT or local time. +If a UT/local indicator is set, the corresponding standard/wall indicator +must also be set. +.PP +The standard/wall and UT/local indicators were designed for +transforming a TZif file's transition times into transitions appropriate +for another time zone specified via a POSIX-style TZ string that lacks rules. +For example, when TZ="EET\*-2EEST" and there is no TZif file "EET\*-2EEST", +the idea was to adapt the transition times from a TZif file with the +well-known name "posixrules" that is present only for this purpose and +is a copy of the file "Europe/Brussels", a file with a different UT offset. +POSIX does not specify this obsolete transformational behavior, +the default rules are installation-dependent, and no implementation +is known to support this feature for timestamps past 2037, +so users desiring (say) Greek time should instead specify +TZ="Europe/Athens" for better historical coverage, falling back on +TZ="EET\*-2EEST,M3.5.0/3,M10.5.0/4" if POSIX conformance is required +and older timestamps need not be handled accurately. +.PP +The +.BR localtime (3) +function +normally uses the first +.B ttinfo +structure in the file +if either +.B tzh_timecnt +is zero or the time argument is less than the first transition time recorded +in the file. +.SS Version 2 format +For version-2-format timezone files, +the above header and data are followed by a second header and data, +identical in format except that +eight bytes are used for each transition time or leap second time. +(Leap second counts remain four bytes.) +After the second header and data comes a newline-enclosed, +POSIX-TZ-environment-variable-style string for use in handling instants +after the last transition time stored in the file +or for all instants if the file has no transitions. +The POSIX-style TZ string is empty (i.e., nothing between the newlines) +if there is no POSIX-style representation for such instants. +If nonempty, the POSIX-style TZ string must agree with the local time +type after the last transition time if present in the eight-byte data; +for example, given the string +.q "WET0WEST,M3.5.0/1,M10.5.0" +then if a last transition time is in July, the transition's local time +type must specify a daylight-saving time abbreviated +.q "WEST" +that is one hour east of UT. +Also, if there is at least one transition, time type 0 is associated +with the time period from the indefinite past up to but not including +the earliest transition time. +.SS Version 3 format +For version-3-format timezone files, the POSIX-TZ-style string may +use two minor extensions to the POSIX TZ format, as described in +.BR newtzset (3). +First, the hours part of its transition times may be signed and range from +\-167 through 167 instead of the POSIX-required unsigned values +from 0 through 24. +Second, DST is in effect all year if it starts +January 1 at 00:00 and ends December 31 at 24:00 plus the difference +between daylight saving and standard time. +.SS Version 4 format +For version-4-format TZif files, +the first leap second record can have a correction that is neither ++1 nor \-1, to represent truncation of the TZif file at the start. +Also, if two or more leap second transitions are present and the last +entry's correction equals the previous one, the last entry +denotes the expiration of the leap second table instead of a leap second; +timestamps after this expiration are unreliable in that future +releases will likely add leap second entries after the expiration, and +the added leap seconds will change how post-expiration timestamps are treated. +.SS Interoperability considerations +Future changes to the format may append more data. +.PP +Version 1 files are considered a legacy format and +should not be generated, as they do not support transition +times after the year 2038. +Readers that understand only Version 1 must ignore +any data that extends beyond the calculated end of the version +1 data block. +.PP +Other than version 1, writers should generate +the lowest version number needed by a file's data. +For example, a writer should generate a version 4 file +only if its leap second table either expires or is truncated at the start. +Likewise, a writer not generating a version 4 file +should generate a version 3 file only if +TZ string extensions are necessary to accurately +model transition times. +.PP +The sequence of time changes defined by the version 1 +header and data block should be a contiguous sub-sequence +of the time changes defined by the version 2+ header and data +block, and by the footer. +This guideline helps obsolescent version 1 readers +agree with current readers about timestamps within the +contiguous sub-sequence. It also lets writers not +supporting obsolescent readers use a +.B tzh_timecnt +of zero +in the version 1 data block to save space. +.PP +When a TZif file contains a leap second table expiration +time, TZif readers should either refuse to process +post-expiration timestamps, or process them as if the expiration +time did not exist (possibly with an error indication). +.PP +Time zone designations should consist of at least three (3) +and no more than six (6) ASCII characters from the set of +alphanumerics, +.q "\*-", +and +.q "+". +This is for compatibility with POSIX requirements for +time zone abbreviations. +.PP +When reading a version 2 or higher file, readers +should ignore the version 1 header and data block except for +the purpose of skipping over them. +.PP +Readers should calculate the total lengths of the +headers and data blocks and check that they all fit within +the actual file size, as part of a validity check for the file. +.PP +When a positive leap second occurs, readers should append an extra +second to the local minute containing the second just before the leap +second. If this occurs when the UTC offset is not a multiple of 60 +seconds, the leap second occurs earlier than the last second of the +local minute and the minute's remaining local seconds are numbered +through 60 instead of the usual 59; the UTC offset is unaffected. +.SS Common interoperability issues +This section documents common problems in reading or writing TZif files. +Most of these are problems in generating TZif files for use by +older readers. +The goals of this section are: +.IP * 2 +to help TZif writers output files that avoid common +pitfalls in older or buggy TZif readers, +.IP * +to help TZif readers avoid common pitfalls when reading +files generated by future TZif writers, and +.IP * +to help any future specification authors see what sort of +problems arise when the TZif format is changed. +.PP +When new versions of the TZif format have been defined, a +design goal has been that a reader can successfully use a TZif +file even if the file is of a later TZif version than what the +reader was designed for. +When complete compatibility was not achieved, an attempt was +made to limit glitches to rarely used timestamps and allow +simple partial workarounds in writers designed to generate +new-version data useful even for older-version readers. +This section attempts to document these compatibility issues and +workarounds, as well as to document other common bugs in +readers. +.PP +Interoperability problems with TZif include the following: +.IP * 2 +Some readers examine only version 1 data. +As a partial workaround, a writer can output as much version 1 +data as possible. +However, a reader should ignore version 1 data, and should use +version 2+ data even if the reader's native timestamps have only +32 bits. +.IP * +Some readers designed for version 2 might mishandle +timestamps after a version 3 or higher file's last transition, because +they cannot parse extensions to POSIX in the TZ-like string. +As a partial workaround, a writer can output more transitions +than necessary, so that only far-future timestamps are +mishandled by version 2 readers. +.IP * +Some readers designed for version 2 do not support +permanent daylight saving time with transitions after 24:00 +\(en e.g., a TZ string +.q "EST5EDT,0/0,J365/25" +denoting permanent Eastern Daylight Time +(\-04). +As a workaround, a writer can substitute standard time +for two time zones east, e.g., +.q "XXX3EDT4,0/0,J365/23" +for a time zone with a never-used standard time (XXX, \-03) +and negative daylight saving time (EDT, \-04) all year. +Alternatively, +as a partial workaround a writer can substitute standard time +for the next time zone east \(en e.g., +.q "AST4" +for permanent +Atlantic Standard Time (\-04). +.IP * +Some readers designed for version 2 or 3, and that require strict +conformance to RFC 8536, reject version 4 files whose leap second +tables are truncated at the start or that end in expiration times. +.IP * +Some readers ignore the footer, and instead predict future +timestamps from the time type of the last transition. +As a partial workaround, a writer can output more transitions +than necessary. +.IP * +Some readers do not use time type 0 for timestamps before +the first transition, in that they infer a time type using a +heuristic that does not always select time type 0. +As a partial workaround, a writer can output a dummy (no-op) +first transition at an early time. +.IP * +Some readers mishandle timestamps before the first +transition that has a timestamp not less than \-2**31. +Readers that support only 32-bit timestamps are likely to be +more prone to this problem, for example, when they process +64-bit transitions only some of which are representable in 32 +bits. +As a partial workaround, a writer can output a dummy +transition at timestamp \-2**31. +.IP * +Some readers mishandle a transition if its timestamp has +the minimum possible signed 64-bit value. +Timestamps less than \-2**59 are not recommended. +.IP * +Some readers mishandle POSIX-style TZ strings that +contain +.q "<" +or +.q ">". +As a partial workaround, a writer can avoid using +.q "<" +or +.q ">" +for time zone abbreviations containing only alphabetic +characters. +.IP * +Many readers mishandle time zone abbreviations that contain +non-ASCII characters. +These characters are not recommended. +.IP * +Some readers may mishandle time zone abbreviations that +contain fewer than 3 or more than 6 characters, or that +contain ASCII characters other than alphanumerics, +.q "\*-", +and +.q "+". +These abbreviations are not recommended. +.IP * +Some readers mishandle TZif files that specify +daylight-saving time UT offsets that are less than the UT +offsets for the corresponding standard time. +These readers do not support locations like Ireland, which +uses the equivalent of the POSIX TZ string +.q "IST\*-1GMT0,M10.5.0,M3.5.0/1", +observing standard time +(IST, +01) in summer and daylight saving time (GMT, +00) in winter. +As a partial workaround, a writer can output data for the +equivalent of the POSIX TZ string +.q "GMT0IST,M3.5.0/1,M10.5.0", +thus swapping standard and daylight saving time. +Although this workaround misidentifies which part of the year +uses daylight saving time, it records UT offsets and time zone +abbreviations correctly. +.IP * +Some readers generate ambiguous timestamps for positive leap seconds +that occur when the UTC offset is not a multiple of 60 seconds. +For example, in a timezone with UTC offset +01:23:45 and with +a positive leap second 78796801 (1972-06-30 23:59:60 UTC), some readers will +map both 78796800 and 78796801 to 01:23:45 local time the next day +instead of mapping the latter to 01:23:46, and they will map 78796815 to +01:23:59 instead of to 01:23:60. +This has not yet been a practical problem, since no civil authority +has observed such UTC offsets since leap seconds were +introduced in 1972. +.PP +Some interoperability problems are reader bugs that +are listed here mostly as warnings to developers of readers. +.IP * 2 +Some readers do not support negative timestamps. +Developers of distributed applications should keep this +in mind if they need to deal with pre-1970 data. +.IP * +Some readers mishandle timestamps before the first +transition that has a nonnegative timestamp. +Readers that do not support negative timestamps are likely to +be more prone to this problem. +.IP * +Some readers mishandle time zone abbreviations like +.q "\*-08" +that contain +.q "+", +.q "\*-", +or digits. +.IP * +Some readers mishandle UT offsets that are out of the +traditional range of \-12 through +12 hours, and so do not +support locations like Kiritimati that are outside this +range. +.IP * +Some readers mishandle UT offsets in the range [\-3599, \-1] +seconds from UT, because they integer-divide the offset by +3600 to get 0 and then display the hour part as +.q "+00". +.IP * +Some readers mishandle UT offsets that are not a multiple +of one hour, or of 15 minutes, or of 1 minute. +.SH SEE ALSO +.BR time (2), +.BR localtime (3), +.BR tzset (3), +.BR tzselect (8), +.BR zdump (8), +.BR zic (8). +.PP +Olson A, Eggert P, Murchison K. The Time Zone Information Format (TZif). +2019 Feb. +.UR https://\:datatracker.ietf.org/\:doc/\:html/\:rfc8536 +Internet RFC 8536 +.UE +.UR https://\:doi.org/\:10.17487/\:RFC8536 +doi:10.17487/RFC8536 +.UE . diff --git a/man5/utmp.5 b/man5/utmp.5 new file mode 100644 index 0000000..4a02964 --- /dev/null +++ b/man5/utmp.5 @@ -0,0 +1,348 @@ +.\" Copyright (c) 1993 Michael Haardt (michael@cantor.informatik.rwth-aachen.de), +.\" Fri Apr 2 11:32:09 MET DST 1993 +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Modified 1993-07-25 by Rik Faith (faith@cs.unc.edu) +.\" Modified 1995-02-26 by Michael Haardt +.\" Modified 1996-07-20 by Michael Haardt +.\" Modified 1997-07-02 by Nicolás Lichtmaier <nick@debian.org> +.\" Modified 2004-10-31 by aeb, following Gwenole Beauchesne +.TH utmp 5 2023-05-03 "Linux man-pages 6.05.01" +.SH NAME +utmp, wtmp \- login records +.SH SYNOPSIS +.nf +.B #include <utmp.h> +.fi +.SH DESCRIPTION +The +.I utmp +file allows one to discover information about who is currently using the +system. +There may be more users currently using the system, because not +all programs use utmp logging. +.PP +.B Warning: +.I utmp +must not be writable by the user class "other", +because many system programs (foolishly) +depend on its integrity. +You risk faked system logfiles and +modifications of system files if you leave +.I utmp +writable to any user other than the owner and group owner of the file. +.PP +The file is a sequence of +.I utmp +structures, +declared as follows in +.I <utmp.h> +(note that this is only one of several definitions +around; details depend on the version of libc): +.PP +.in +4n +.EX +/* Values for ut_type field, below */ +\& +#define EMPTY 0 /* Record does not contain valid info + (formerly known as UT_UNKNOWN on Linux) */ +#define RUN_LVL 1 /* Change in system run\-level (see + \fBinit\fP(1)) */ +#define BOOT_TIME 2 /* Time of system boot (in \fIut_tv\fP) */ +#define NEW_TIME 3 /* Time after system clock change + (in \fIut_tv\fP) */ +#define OLD_TIME 4 /* Time before system clock change + (in \fIut_tv\fP) */ +#define INIT_PROCESS 5 /* Process spawned by \fBinit\fP(1) */ +#define LOGIN_PROCESS 6 /* Session leader process for user login */ +#define USER_PROCESS 7 /* Normal process */ +#define DEAD_PROCESS 8 /* Terminated process */ +#define ACCOUNTING 9 /* Not implemented */ +\& +#define UT_LINESIZE 32 +#define UT_NAMESIZE 32 +#define UT_HOSTSIZE 256 +\& +struct exit_status { /* Type for ut_exit, below */ + short e_termination; /* Process termination status */ + short e_exit; /* Process exit status */ +}; +\& +struct utmp { + short ut_type; /* Type of record */ + pid_t ut_pid; /* PID of login process */ + char ut_line[UT_LINESIZE]; /* Device name of tty \- "/dev/" */ + char ut_id[4]; /* Terminal name suffix, + or inittab(5) ID */ + char ut_user[UT_NAMESIZE]; /* Username */ + char ut_host[UT_HOSTSIZE]; /* Hostname for remote login, or + kernel version for run\-level + messages */ + struct exit_status ut_exit; /* Exit status of a process + marked as DEAD_PROCESS; not + used by Linux init(1) */ + /* The ut_session and ut_tv fields must be the same size when + compiled 32\- and 64\-bit. This allows data files and shared + memory to be shared between 32\- and 64\-bit applications. */ +#if __WORDSIZE == 64 && defined __WORDSIZE_COMPAT32 + int32_t ut_session; /* Session ID (\fBgetsid\fP(2)), + used for windowing */ + struct { + int32_t tv_sec; /* Seconds */ + int32_t tv_usec; /* Microseconds */ + } ut_tv; /* Time entry was made */ +#else + long ut_session; /* Session ID */ + struct timeval ut_tv; /* Time entry was made */ +#endif +\& + int32_t ut_addr_v6[4]; /* Internet address of remote + host; IPv4 address uses + just ut_addr_v6[0] */ + char __unused[20]; /* Reserved for future use */ +}; +\& +/* Backward compatibility hacks */ +#define ut_name ut_user +#ifndef _NO_UT_TIME +#define ut_time ut_tv.tv_sec +#endif +#define ut_xtime ut_tv.tv_sec +#define ut_addr ut_addr_v6[0] +.EE +.in +.PP +This structure gives the name of the special file associated with the +user's terminal, the user's login name, and the time of login in the form +of +.BR time (2). +String fields are terminated by a null byte (\[aq]\e0\[aq]) +if they are shorter than the size +of the field. +.PP +The first entries ever created result from +.BR init (1) +processing +.BR inittab (5). +Before an entry is processed, though, +.BR init (1) +cleans up utmp by setting \fIut_type\fP to \fBDEAD_PROCESS\fP, clearing +\fIut_user\fP, \fIut_host\fP, and \fIut_time\fP with null bytes for each +record which \fIut_type\fP is not \fBDEAD_PROCESS\fP or \fBRUN_LVL\fP +and where no process with PID \fIut_pid\fP exists. +If no empty record +with the needed \fIut_id\fP can be found, +.BR init (1) +creates a new one. +It sets \fIut_id\fP from the inittab, \fIut_pid\fP and \fIut_time\fP to the +current values, and \fIut_type\fP to \fBINIT_PROCESS\fP. +.PP +.BR mingetty (8) +(or +.BR agetty (8)) +locates the entry by the PID, changes \fIut_type\fP to +\fBLOGIN_PROCESS\fP, changes \fIut_time\fP, sets \fIut_line\fP, and waits +for connection to be established. +.BR login (1), +after a user has been +authenticated, changes \fIut_type\fP to \fBUSER_PROCESS\fP, changes +\fIut_time\fP, and sets \fIut_host\fP and \fIut_addr\fP. +Depending on +.BR mingetty (8) +(or +.BR agetty (8)) +and +.BR login (1), +records may be located by +\fIut_line\fP instead of the preferable \fIut_pid\fP. +.PP +When +.BR init (1) +finds that a process has exited, it locates its utmp entry by +.IR ut_pid , +sets +.I ut_type +to +.BR DEAD_PROCESS , +and clears +.IR ut_user , +.IR ut_host , +and +.I ut_time +with null bytes. +.PP +.BR xterm (1) +and other terminal emulators directly create a +\fBUSER_PROCESS\fP record and generate the \fIut_id\fP by using the +string that suffix part of the terminal name (the characters +following +.IR /dev/ [pt] ty ). +If they find a \fBDEAD_PROCESS\fP for this ID, +they recycle it, otherwise they create a new entry. +If they can, they +will mark it as \fBDEAD_PROCESS\fP on exiting and it is advised that +they null \fIut_line\fP, \fIut_time\fP, \fIut_user\fP, and \fIut_host\fP +as well. +.PP +.BR telnetd (8) +sets up a \fBLOGIN_PROCESS\fP entry and leaves the rest to +.BR login (1) +as usual. +After the telnet session ends, +.BR telnetd (8) +cleans up utmp in the described way. +.PP +The \fIwtmp\fP file records all logins and logouts. +Its format is exactly like \fIutmp\fP except that a null username +indicates a logout +on the associated terminal. +Furthermore, the terminal name \fB\[ti]\fP +with username \fBshutdown\fP or \fBreboot\fP indicates a system +shutdown or reboot and the pair of terminal names \fB|\fP/\fB}\fP +logs the old/new system time when +.BR date (1) +changes it. +\fIwtmp\fP is maintained by +.BR login (1), +.BR init (1), +and some versions of +.BR getty (8) +(e.g., +.BR mingetty (8) +or +.BR agetty (8)). +None of these programs creates the file, so if it is +removed, record-keeping is turned off. +.SH FILES +.I /var/run/utmp +.br +.I /var/log/wtmp +.SH VERSIONS +POSIX.1 does not specify a +.I utmp +structure, but rather one named +.I utmpx +(as part of the XSI extension), +with specifications for the fields +.IR ut_type , +.IR ut_pid , +.IR ut_line , +.IR ut_id , +.IR ut_user , +and +.IR ut_tv . +POSIX.1 does not specify the lengths of the +.I ut_line +and +.I ut_user +fields. +.PP +Linux defines the +.I utmpx +structure to be the same as the +.I utmp +structure. +.SH STANDARDS +Linux. +.SH HISTORY +Linux utmp entries conform neither to v7/BSD nor to System V; they are a +mix of the two. +.PP +v7/BSD has fewer fields; most importantly it lacks +\fIut_type\fP, which causes native v7/BSD-like programs to display (for +example) dead or login entries. +Further, there is no configuration file +which allocates slots to sessions. +BSD does so because it lacks \fIut_id\fP fields. +.PP +In Linux (as in System V), the \fIut_id\fP field of a +record will never change once it has been set, which reserves that slot +without needing a configuration file. +Clearing \fIut_id\fP may result +in race conditions leading to corrupted utmp entries and potential +security holes. +Clearing the abovementioned fields by filling them +with null bytes is not required by System V semantics, +but makes it possible to run +many programs which assume BSD semantics and which do not modify utmp. +Linux uses the BSD conventions for line contents, as documented above. +.PP +.\" mtk: What is the referrent of "them" in the following sentence? +.\" System V only uses the type field to mark them and logs +.\" informative messages such as \fB"new time"\fP in the line field. +System V has no \fIut_host\fP or \fIut_addr_v6\fP fields. +.SH NOTES +Unlike various other +systems, where utmp logging can be disabled by removing the file, utmp +must always exist on Linux. +If you want to disable +.BR who (1), +then do not make utmp world readable. +.PP +The file format is machine-dependent, so it is recommended that it be +processed only on the machine architecture where it was created. +.PP +Note that on \fIbiarch\fP platforms, that is, systems which can run both +32-bit and 64-bit applications (x86-64, ppc64, s390x, etc.), +\fIut_tv\fP is the same size in 32-bit mode as in 64-bit mode. +The same goes for \fIut_session\fP and \fIut_time\fP if they are present. +This allows data files and shared memory to be shared between +32-bit and 64-bit applications. +This is achieved by changing the type of +.I ut_session +to +.IR int32_t , +and that of +.I ut_tv +to a struct with two +.I int32_t +fields +.I tv_sec +and +.IR tv_usec . +Since \fIut_tv\fP may not be the same as \fIstruct timeval\fP, +then instead of the call: +.PP +.in +4n +.EX +gettimeofday((struct timeval *) &ut.ut_tv, NULL); +.EE +.in +.PP +the following method of setting this field is recommended: +.PP +.in +4n +.EX +struct utmp ut; +struct timeval tv; +\& +gettimeofday(&tv, NULL); +ut.ut_tv.tv_sec = tv.tv_sec; +ut.ut_tv.tv_usec = tv.tv_usec; +.EE +.in +.\" .PP +.\" Note that the \fIutmp\fP struct from libc5 has changed in libc6. +.\" Because of this, +.\" binaries using the old libc5 struct will corrupt +.\" .IR /var/run/utmp " and/or " /var/log/wtmp . +.\" .SH BUGS +.\" This man page is based on the libc5 one, things may work differently now. +.SH SEE ALSO +.BR ac (1), +.BR date (1), +.BR init (1), +.BR last (1), +.BR login (1), +.BR logname (1), +.BR lslogins (1), +.BR users (1), +.BR utmpdump (1), +.BR who (1), +.BR getutent (3), +.BR getutmp (3), +.BR login (3), +.BR logout (3), +.BR logwtmp (3), +.BR updwtmp (3) diff --git a/man5/utmpx.5 b/man5/utmpx.5 new file mode 100644 index 0000000..1fa9e5a --- /dev/null +++ b/man5/utmpx.5 @@ -0,0 +1 @@ +.so man5/utmp.5 diff --git a/man5/wtmp.5 b/man5/wtmp.5 new file mode 100644 index 0000000..1fa9e5a --- /dev/null +++ b/man5/wtmp.5 @@ -0,0 +1 @@ +.so man5/utmp.5 |