NAME
exit, _Exit
— perform normal program
termination
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<stdlib.h>
void
exit(int
status);
void
_Exit(int
status);
DESCRIPTION
The
exit()
and _Exit() functions terminate a process.
Before termination,
exit()
performs the following functions in the order listed:
- Call all functions registered with the __cxa_atexit(3) function (which are typically destructors from the loaded dynamic objects), and the functions registered with the atexit(3) function, in the reverse order of their registration.
- Flush all open output streams.
- Close all open streams.
The
_Exit()
function terminates without calling the functions registered with the
atexit(3) function, and may or may not perform the other
actions listed. The FreeBSD implementation of the
_Exit() function does not call destructors
registered with
__cxa_atexit(3,) does not flush buffers, and does not close
streams.
Both functions make the low-order eight bits of the status argument available to a parent process which has called a wait(2)-family function.
The C Standard (ISO/IEC 9899:1999
(“ISO C99”)) defines the values
0, EXIT_SUCCESS, and
EXIT_FAILURE as possible values of
status. Cooperating processes may use other values; in
a program which might be called by a mail transfer agent, the values
described in
sysexits(3) may be used to provide more information to the
parent process.
Note that
exit() does
nothing to prevent bottomless recursion should a function registered using
atexit(3) itself call exit(). Such
functions must call _Exit() instead (although this
has other effects as well which may not be desired).
RETURN VALUES
The exit() and
_Exit() functions never return.
SEE ALSO
_exit(2), abort2(2), wait(2), at_quick_exit(3), atexit(3), intro(3), quick_exit(3), sysexits(3), tmpfile(3)
STANDARDS
The exit() and
_Exit() functions conform to
ISO/IEC 9899:1999
(“ISO C99”).
HISTORY
The exit() function appeared in
Version 1 AT&T UNIX.