Name

exit — cause normal process termination

Synopsis

#include <stdlib.h>
void exit( int status);
 

DESCRIPTION

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.

RETURN VALUE

The exit() function does not return.

CONFORMING TO

SVr4, 4.3BSD, POSIX.1-2001, C89, C99.

NOTES

It is undefined what happens if one of the functions registered using atexit(3) and on_exit(3) calls either exit() or longjmp(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. If the parent was waiting on the child it is notified of the exit status. In both cases the exiting process dies immediately. If the parent has not indicated that it is not interested in the exit status, but is not waiting, the exiting process turns into a "zombie" process (which is nothing but a container for the single byte representing the exit status) so that the parent can learn the exit status when it later calls one of the wait(2) functions.

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.

If the 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.

SEE ALSO

_exit(2), setpgid(2), wait(2), atexit(3), on_exit(3), tmpfile(3)

COLOPHON

This page is part of release 3.24 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


  Copyright (C) 2001 Andries Brouwer <aebcwi.nl>.

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.