exit(3) -- Linux man page
NAME
exit - cause normal program termination
SYNOPSIS
#include <stdlib.h>
void exit(int status);
DESCRIPTION
The exit() function causes normal program termination and the
the value of status & 0377 is returned to the parent
(see
wait(2)).
All functions registered with atexit() and on_exit()
are called in the reverse order of their registration,
and all open streams are flushed and closed.
Files created by tmpfile() are removed.
The C standard specifies two defines 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
SVID 3, POSIX, BSD 4.3, ISO 9899 (``ANSI C'')
NOTES
During the exit processing, it is possible to register additional
functions with atexit() and on_exit().
Always the last-registered function is removed from the chain
of registered functions, and invoked.
It is undefined what happens if during this processing
either exit() or longjmp() is called.
The use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable
(to non-Unix environments) than that 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() 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
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 ALSO
_exit(2),
wait(2),
atexit(3),
on_exit(3),
tmpfile(3)
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