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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
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EXIT(3) Linux Programmer's Manual EXIT(3)
exit - cause normal process termination
#include <stdlib.h>
void exit(int status);
The exit() function causes normal process termination and the value
of status & 0377 is returned to the parent (see wait(2)).
All functions registered with atexit(3) and on_exit(3) are called, in
the reverse order of their registration. (It is possible for one of
these functions to use atexit(3) or 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 _exit(2), or kills itself with a signal), then none
of the remaining functions is called, and further exit processing (in
particular, flushing of stdio(3) streams) is abandoned. If a
function has been registered multiple times using atexit(3) or
on_exit(3), then it is called as many times as it was registered.
All open stdio(3) streams are flushed and closed. Files created by
tmpfile(3) are removed.
The C standard specifies two constants, EXIT_SUCCESS and
EXIT_FAILURE, that may be passed to exit() to indicate successful or
unsuccessful termination, respectively.
The exit() function does not return.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────┬───────────────┬─────────────────────┐
│Interface │ Attribute │ Value │
├──────────┼───────────────┼─────────────────────┤
│exit() │ Thread safety │ MT-Unsafe race:exit │
└──────────┴───────────────┴─────────────────────┘
The exit() function uses a global variable that is not protected, so
it is not thread-safe.
POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.
The behavior is undefined if one of the functions registered using
atexit(3) and on_exit(3) calls either exit() or longjmp(3). Note
that a call to execve(2) removes registrations created using
atexit(3) and on_exit(3).
The use of EXIT_SUCCESS and 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.
BSD has attempted to standardize exit codes; see the file
<sysexits.h>.
After exit(), the exit status must be transmitted to the parent
process. There are three cases:
· If the parent has set SA_NOCLDWAIT, or has set the SIGCHLD handler
to SIG_IGN, the status is discarded and the child dies
immediately.
· If the parent was waiting on the child, it is notified of the exit
status and the child dies immediately.
· 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 waitpid(2) (or similar) to learn the
termination status of the child; at that point the zombie process
slot is released.
If the implementation supports the SIGCHLD signal, this signal is
sent to the parent. If the parent has set SA_NOCLDWAIT, it is
undefined whether a SIGCHLD signal is sent.
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 SIGHUP signal, and the terminal is disassociated from this
session, allowing it to be acquired by a new controlling process.
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 SIGHUP signal followed by a SIGCONT signal will be sent to
each process in this process group. See setpgid(2) for an
explanation of orphaned process groups.
Except in the above cases, where the signalled processes may be
children of the terminating process, termination of a process does
not in general cause a signal to be sent to children of that process.
However, a process can use the prctl(2) PR_SET_PDEATHSIG operation to
arrange that it receives a signal if its parent terminates.
_exit(2), get_robust_list(2), setpgid(2), wait(2), atexit(3),
on_exit(3), tmpfile(3)
This page is part of release 4.15 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2017-09-15 EXIT(3)
Pages that refer to this page: man(1), _exit(2), kill(2), vfork(2), wait(2), abort(3), assert(3), assert_perror(3), atexit(3), err(3), error(3), on_exit(3), pthread_create(3), pthread_detach(3), pthread_exit(3), setjmp(3), stdin(3), stdio(3), tmpfile(3)
Copyright and license for this manual page
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