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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.
SVr4, 4.3BSD, POSIX.1-2001, C89, C99.
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.
_exit(2), setpgid(2), wait(2), atexit(3), on_exit(3), tmpfile(3)
This page is part of release 3.32 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/.
Linux 2009-09-20 EXIT(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface