diff options
Diffstat (limited to 'man3/exit.3')
| -rw-r--r-- | man3/exit.3 | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/man3/exit.3 b/man3/exit.3 new file mode 100644 index 0000000..f51c557 --- /dev/null +++ b/man3/exit.3 @@ -0,0 +1,203 @@ +'\" t +.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>. +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" FIXME . There are a lot of other process termination actions that +.\" could be listed on this page. See, for example, the list in the +.\" POSIX exit(3p) page. +.\" +.TH exit 3 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +exit \- cause normal process termination +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <stdlib.h> +.PP +.BI "[[noreturn]] void exit(int " status ); +.fi +.SH DESCRIPTION +The +.BR exit () +function causes normal process termination and the least significant byte of +.I status +(i.e., \fIstatus & 0xFF\fP) is returned to the parent (see +.BR wait (2)). +.PP +All functions registered with +.BR atexit (3) +and +.BR on_exit (3) +are called, in the reverse order of their registration. +(It is possible for one of these functions to use +.BR atexit (3) +or +.BR on_exit (3) +to register an additional +function to be executed during exit processing; +the new registration is added to the front of the list of functions +that remain to be called.) +If one of these functions does not return +(e.g., it calls +.BR _exit (2), +or kills itself with a signal), +then none of the remaining functions is called, +and further exit processing (in particular, flushing of +.BR stdio (3) +streams) is abandoned. +If a function has been registered multiple times using +.BR atexit (3) +or +.BR on_exit (3), +then it is called as many times as it was registered. +.PP +All open +.BR stdio (3) +streams are flushed and closed. +Files created by +.BR tmpfile (3) +are removed. +.PP +The C standard specifies two constants, +\fBEXIT_SUCCESS\fP and \fBEXIT_FAILURE\fP, +that may be passed to +.BR exit () +to indicate successful or unsuccessful +termination, respectively. +.SH RETURN VALUE +The +.BR exit () +function does not return. +.SH ATTRIBUTES +For an explanation of the terms used in this section, see +.BR attributes (7). +.TS +allbox; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR exit () +T} Thread safety MT-Unsafe race:exit +.TE +.sp 1 +.PP +The +.BR exit () +function uses a global variable that is not protected, +so it is not thread-safe. +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +C89, POSIX.1-2001, SVr4, 4.3BSD. +.SH NOTES +The behavior is undefined if one of the functions registered using +.BR atexit (3) +and +.BR on_exit (3) +calls either +.BR exit () +or +.BR longjmp (3). +Note that a call to +.BR execve (2) +removes registrations created using +.BR atexit (3) +and +.BR on_exit (3). +.PP +The use of +.B EXIT_SUCCESS +and +.B EXIT_FAILURE +is slightly more portable +(to non-UNIX environments) than the use of 0 and some nonzero value +like 1 or \-1. +In particular, VMS uses a different convention. +.PP +BSD has attempted to standardize exit codes +(which some C libraries such as the GNU C library have also adopted); +see the file +.IR <sysexits.h> . +.PP +After +.BR exit (), +the exit status must be transmitted to the +parent process. +There are three cases: +.IP \[bu] 3 +If the parent has set +.BR SA_NOCLDWAIT , +or has set the +.B SIGCHLD +handler to +.BR SIG_IGN , +the status is discarded and the child dies immediately. +.IP \[bu] +If the parent was waiting on the child, +it is notified of the exit status and the child dies immediately. +.IP \[bu] +Otherwise, +the child becomes a "zombie" process: +most of the process resources are recycled, +but a slot containing minimal information about the child process +(termination status, resource usage statistics) is retained in process table. +This allows the parent to subsequently use +.BR waitpid (2) +(or similar) to learn the termination status of the child; +at that point the zombie process slot is released. +.PP +If the implementation supports the +.B SIGCHLD +signal, this signal +is sent to the parent. +If the parent has set +.BR SA_NOCLDWAIT , +it is undefined whether a +.B SIGCHLD +signal is sent. +.\" +.SS Signals sent to other processes +If the exiting process is a session leader and its controlling terminal +is the controlling terminal of the session, then each process in +the foreground process group of this controlling terminal +is sent a +.B SIGHUP +signal, and the terminal is disassociated +from this session, allowing it to be acquired by a new controlling +process. +.PP +If the exit of the process causes a process group to become orphaned, +and if any member of the newly orphaned process group is stopped, +then a +.B SIGHUP +signal followed by a +.B SIGCONT +signal will be +sent to each process in this process group. +See +.BR setpgid (2) +for an explanation of orphaned process groups. +.PP +Except in the above cases, +where the signalled processes may be children of the terminating process, +termination of a process does +.I not +in general cause a signal to be sent to children of that process. +However, a process can use the +.BR prctl (2) +.B PR_SET_PDEATHSIG +operation to arrange that it receives a signal if its parent terminates. +.SH SEE ALSO +.BR _exit (2), +.BR get_robust_list (2), +.BR setpgid (2), +.BR wait (2), +.BR atexit (3), +.BR on_exit (3), +.BR tmpfile (3) |