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diff --git a/man/man1/su.1 b/man/man1/su.1 new file mode 100644 index 0000000..7639e76 --- /dev/null +++ b/man/man1/su.1 @@ -0,0 +1,448 @@ +'\" t +.\" Title: su +.\" Author: Julianne Frances Haugh +.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/> +.\" Date: 01/23/2020 +.\" Manual: User Commands +.\" Source: shadow-utils 4.8.1 +.\" Language: English +.\" +.TH "SU" "1" "01/23/2020" "shadow\-utils 4\&.8\&.1" "User Commands" +.\" ----------------------------------------------------------------- +.\" * Define some portability stuff +.\" ----------------------------------------------------------------- +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.\" http://bugs.debian.org/507673 +.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html +.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +.ie \n(.g .ds Aq \(aq +.el .ds Aq ' +.\" ----------------------------------------------------------------- +.\" * set default formatting +.\" ----------------------------------------------------------------- +.\" disable hyphenation +.nh +.\" disable justification (adjust text to left margin only) +.ad l +.\" ----------------------------------------------------------------- +.\" * MAIN CONTENT STARTS HERE * +.\" ----------------------------------------------------------------- +.SH "NAME" +su \- change user ID or become superuser +.SH "SYNOPSIS" +.HP \w'\fBsu\fR\ 'u +\fBsu\fR [\fIoptions\fR] [\fI\-\fR] [\fIusername\fR\ [\ \fIargs\fR\ ]] +.SH "DESCRIPTION" +.PP +The +\fBsu\fR +command is used to become another user during a login session\&. Invoked without a +\fBusername\fR, +\fBsu\fR +defaults to becoming the superuser\&. The +\fB\-\fR +option may be used to provide an environment similar to what the user would expect had the user logged in directly\&. The +\fB\-c\fR +option may be used to treat the next argument as a command by most shells\&. +.PP +Options are recognized everywhere in the argument list\&. You can use the +\fB\-\-\fR +argument to stop option parsing\&. The +\fB\-\fR +option is special: it is also recognized after +\fB\-\-\fR, but has to be placed before +\fBusername\fR\&. +.PP +The user will be prompted for a password, if appropriate\&. Invalid passwords will produce an error message\&. All attempts, both valid and invalid, are logged to detect abuse of the system\&. +.PP +The current environment is passed to the new shell\&. The value of +\fB$PATH\fR +is reset to +/bin:/usr/bin +for normal users, or +/sbin:/bin:/usr/sbin:/usr/bin +for the superuser\&. This may be changed with the +\fBENV_PATH\fR +and +\fBENV_SUPATH\fR +definitions in +/etc/login\&.defs\&. +.PP +A subsystem login is indicated by the presence of a "*" as the first character of the login shell\&. The given home directory will be used as the root of a new file system which the user is actually logged into\&. +.SH "OPTIONS" +.PP +The options which apply to the +\fBsu\fR +command are: +.PP +\fB\-c\fR, \fB\-\-command\fR\ \&\fICOMMAND\fR +.RS 4 +Specify a command that will be invoked by the shell using its +\fB\-c\fR\&. +.sp +The executed command will have no controlling terminal\&. This option cannot be used to execute interactive programs which need a controlling TTY\&. +.RE +.PP +\fB\-\fR, \fB\-l\fR, \fB\-\-login\fR +.RS 4 +Provide an environment similar to what the user would expect had the user logged in directly\&. +.sp +When +\fB\-\fR +is used, it must be specified before any +\fBusername\fR\&. For portability it is recommended to use it as last option, before any +\fBusername\fR\&. The other forms (\fB\-l\fR +and +\fB\-\-login\fR) do not have this restriction\&. +.RE +.PP +\fB\-s\fR, \fB\-\-shell\fR\ \&\fISHELL\fR +.RS 4 +The shell that will be invoked\&. +.sp +The invoked shell is chosen from (highest priority first): +.PP +.RS 4 +The shell specified with \-\-shell\&. +.RE +.PP +.RS 4 +If +\fB\-\-preserve\-environment\fR +is used, the shell specified by the +\fB$SHELL\fR +environment variable\&. +.RE +.PP +.RS 4 +The shell indicated in the +/etc/passwd +entry for the target user\&. +.RE +.PP +.RS 4 +/bin/sh +if a shell could not be found by any above method\&. +.RE +.sp +If the target user has a restricted shell (i\&.e\&. the shell field of this user\*(Aqs entry in +/etc/passwd +is not listed in +/etc/shells), then the +\fB\-\-shell\fR +option or the +\fB$SHELL\fR +environment variable won\*(Aqt be taken into account, unless +\fBsu\fR +is called by root\&. +.RE +.PP +\fB\-m\fR, \fB\-p\fR, \fB\-\-preserve\-environment\fR +.RS 4 +Preserve the current environment, except for: +.PP +\fB$PATH\fR +.RS 4 +reset according to the +/etc/login\&.defs +options +\fBENV_PATH\fR +or +\fBENV_SUPATH\fR +(see below); +.RE +.PP +\fB$IFS\fR +.RS 4 +reset to +\(lq<space><tab><newline>\(rq, if it was set\&. +.RE +.sp +If the target user has a restricted shell, this option has no effect (unless +\fBsu\fR +is called by root)\&. +.sp +Note that the default behavior for the environment is the following: +.PP +.RS 4 +The +\fB$HOME\fR, +\fB$SHELL\fR, +\fB$USER\fR, +\fB$LOGNAME\fR, +\fB$PATH\fR, and +\fB$IFS\fR +environment variables are reset\&. +.RE +.PP +.RS 4 +If +\fB\-\-login\fR +is not used, the environment is copied, except for the variables above\&. +.RE +.PP +.RS 4 +If +\fB\-\-login\fR +is used, the +\fB$TERM\fR, +\fB$COLORTERM\fR, +\fB$DISPLAY\fR, and +\fB$XAUTHORITY\fR +environment variables are copied if they were set\&. +.RE +.PP +.RS 4 +If +\fB\-\-login\fR +is used, the +\fB$TZ\fR, +\fB$HZ\fR, and +\fB$MAIL\fR +environment variables are set according to the +/etc/login\&.defs +options +\fBENV_TZ\fR, +\fBENV_HZ\fR, +\fBMAIL_DIR\fR, and +\fBMAIL_FILE\fR +(see below)\&. +.RE +.PP +.RS 4 +If +\fB\-\-login\fR +is used, other environment variables might be set by the +\fBENVIRON_FILE\fR +file (see below)\&. +.RE +.sp +.RE +.SH "CAVEATS" +.PP +This version of +\fBsu\fR +has many compilation options, only some of which may be in use at any particular site\&. +.SH "CONFIGURATION" +.PP +The following configuration variables in +/etc/login\&.defs +change the behavior of this tool: +.PP +\fBCONSOLE\fR (string) +.RS 4 +If defined, either full pathname of a file containing device names (one per line) or a ":" delimited list of device names\&. Root logins will be allowed only upon these devices\&. +.sp +If not defined, root will be allowed on any device\&. +.sp +The device should be specified without the /dev/ prefix\&. +.RE +.PP +\fBCONSOLE_GROUPS\fR (string) +.RS 4 +List of groups to add to the user\*(Aqs supplementary groups set when logging in on the console (as determined by the CONSOLE setting)\&. Default is none\&. + +Use with caution \- it is possible for users to gain permanent access to these groups, even when not logged in on the console\&. +.RE +.PP +\fBDEFAULT_HOME\fR (boolean) +.RS 4 +Indicate if login is allowed if we can\*(Aqt cd to the home directory\&. Default is no\&. +.sp +If set to +\fIyes\fR, the user will login in the root (/) directory if it is not possible to cd to her home directory\&. +.RE +.PP +\fBENV_HZ\fR (string) +.RS 4 +If set, it will be used to define the HZ environment variable when a user login\&. The value must be preceded by +\fIHZ=\fR\&. A common value on Linux is +\fIHZ=100\fR\&. +.RE +.PP +\fBENVIRON_FILE\fR (string) +.RS 4 +If this file exists and is readable, login environment will be read from it\&. Every line should be in the form name=value\&. +.sp +Lines starting with a # are treated as comment lines and ignored\&. +.RE +.PP +\fBENV_PATH\fR (string) +.RS 4 +If set, it will be used to define the PATH environment variable when a regular user login\&. The value is a colon separated list of paths (for example +\fI/bin:/usr/bin\fR) and can be preceded by +\fIPATH=\fR\&. The default value is +\fIPATH=/bin:/usr/bin\fR\&. +.RE +.PP +\fBENV_SUPATH\fR (string) +.RS 4 +If set, it will be used to define the PATH environment variable when the superuser login\&. The value is a colon separated list of paths (for example +\fI/sbin:/bin:/usr/sbin:/usr/bin\fR) and can be preceded by +\fIPATH=\fR\&. The default value is +\fIPATH=/sbin:/bin:/usr/sbin:/usr/bin\fR\&. +.RE +.PP +\fBENV_TZ\fR (string) +.RS 4 +If set, it will be used to define the TZ environment variable when a user login\&. The value can be the name of a timezone preceded by +\fITZ=\fR +(for example +\fITZ=CST6CDT\fR), or the full path to the file containing the timezone specification (for example +/etc/tzname)\&. +.sp +If a full path is specified but the file does not exist or cannot be read, the default is to use +\fITZ=CST6CDT\fR\&. +.RE +.PP +\fBLOGIN_STRING\fR (string) +.RS 4 +The string used for prompting a password\&. The default is to use "Password: ", or a translation of that string\&. If you set this variable, the prompt will not be translated\&. +.sp +If the string contains +\fI%s\fR, this will be replaced by the user\*(Aqs name\&. +.RE +.PP +\fBMAIL_CHECK_ENAB\fR (boolean) +.RS 4 +Enable checking and display of mailbox status upon login\&. +.sp +You should disable it if the shell startup files already check for mail ("mailx \-e" or equivalent)\&. +.RE +.PP +\fBMAIL_DIR\fR (string) +.RS 4 +The mail spool directory\&. This is needed to manipulate the mailbox when its corresponding user account is modified or deleted\&. If not specified, a compile\-time default is used\&. +.RE +.PP +\fBMAIL_FILE\fR (string) +.RS 4 +Defines the location of the users mail spool files relatively to their home directory\&. +.RE +.PP +The +\fBMAIL_DIR\fR +and +\fBMAIL_FILE\fR +variables are used by +\fBuseradd\fR, +\fBusermod\fR, and +\fBuserdel\fR +to create, move, or delete the user\*(Aqs mail spool\&. +.PP +If +\fBMAIL_CHECK_ENAB\fR +is set to +\fIyes\fR, they are also used to define the +\fBMAIL\fR +environment variable\&. +.PP +\fBQUOTAS_ENAB\fR (boolean) +.RS 4 +Enable setting of resource limits from +/etc/limits +and ulimit, umask, and niceness from the user\*(Aqs passwd gecos field\&. +.RE +.PP +\fBSULOG_FILE\fR (string) +.RS 4 +If defined, all su activity is logged to this file\&. +.RE +.PP +\fBSU_NAME\fR (string) +.RS 4 +If defined, the command name to display when running "su \-"\&. For example, if this is defined as "su" then a "ps" will display the command is "\-su"\&. If not defined, then "ps" would display the name of the shell actually being run, e\&.g\&. something like "\-sh"\&. +.RE +.PP +\fBSU_WHEEL_ONLY\fR (boolean) +.RS 4 +If +\fIyes\fR, the user must be listed as a member of the first gid 0 group in +/etc/group +(called +\fIroot\fR +on most Linux systems) to be able to +\fBsu\fR +to uid 0 accounts\&. If the group doesn\*(Aqt exist or is empty, no one will be able to +\fBsu\fR +to uid 0\&. +.RE +.PP +\fBSYSLOG_SU_ENAB\fR (boolean) +.RS 4 +Enable "syslog" logging of +\fBsu\fR +activity \- in addition to sulog file logging\&. +.RE +.PP +\fBUSERGROUPS_ENAB\fR (boolean) +.RS 4 +Enable setting of the umask group bits to be the same as owner bits (examples: 022 \-> 002, 077 \-> 007) for non\-root users, if the uid is the same as gid, and username is the same as the primary group name\&. +.sp +If set to +\fIyes\fR, +\fBuserdel\fR +will remove the user\*(Aqs group if it contains no more members, and +\fBuseradd\fR +will create by default a group with the name of the user\&. +.RE +.SH "FILES" +.PP +/etc/passwd +.RS 4 +User account information\&. +.RE +.PP +/etc/shadow +.RS 4 +Secure user account information\&. +.RE +.PP +/etc/login\&.defs +.RS 4 +Shadow password suite configuration\&. +.RE +.SH "EXIT VALUES" +.PP +On success, +\fBsu\fR +returns the exit value of the command it executed\&. +.PP +If this command was terminated by a signal, +\fBsu\fR +returns the number of this signal plus 128\&. +.PP +If su has to kill the command (because it was asked to terminate, and the command did not terminate in time), +\fBsu\fR +returns 255\&. +.PP +Some exit values from +\fBsu\fR +are independent from the executed command: +.PP +\fI0\fR +.RS 4 +success (\fB\-\-help\fR +only) +.RE +.PP +\fI1\fR +.RS 4 +System or authentication failure +.RE +.PP +\fI126\fR +.RS 4 +The requested command was not found +.RE +.PP +\fI127\fR +.RS 4 +The requested command could not be executed +.RE +.SH "SEE ALSO" +.PP +\fBlogin\fR(1), +\fBlogin.defs\fR(5), +\fBsg\fR(1), +\fBsh\fR(1)\&. |