EXIT(3) Linux Programmer's Manual EXIT(3)
exit - cause normal process termination
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() and on_exit() are called, in the
reverse order of their registration. (It is possible for one of these
functions to use atexit() or on_exit() to register an additional func-
tion to be executed during exit processing; the new registration is
added to the front of the list of functions that remain to be called.)
All open streams are flushed and closed. Files created by tmpfile()
The C standard specifies two constants, EXIT_SUCCESS and EXIT_FAILURE,
that may be passed to exit() to indicate successful or unsuccessful
The exit() function does not return.
SVr4, 4.3BSD, POSIX.1-2001.
It is undefined what happens if one of the functions registered using
atexit() and on_exit() calls either exit() or longjmp().
The use of EXIT_SUCCESS and EXIT_FAILURE is slightly more portable (to
non-Unix environments) than that of 0 and some non-zero 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 pro-
cess. 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 sta-
tus) 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 is the
controlling terminal of the session, then each process in the fore-
ground process group of this controlling terminal is sent a SIGHUP sig-
nal, 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 pro-
cess in this process group.
_exit(2), wait(2), atexit(3), on_exit(3), tmpfile(3)