_exit, _Exit - terminate the calling process
#include <unistd.h>
void _exit(int status);
#include <stdlib.h>
void _Exit(int status);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
_Exit():
_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
_exit() terminates the calling process "immediately". Any open
file descriptors belonging to the process are closed. Any children of the
process are inherited by
init(1) (or by the nearest
"subreaper" process as defined through the use of the
prctl(2)
PR_SET_CHILD_SUBREAPER operation). The process's parent
is sent a
SIGCHLD signal.
The value
status & 0xFF is returned to the parent process as the
process's exit status, and can be collected by the parent using one of the
wait(2) family of calls.
The function
_Exit() is equivalent to
_exit().
These functions do not return.
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD. The function
_Exit() was
introduced by C99.
For a discussion on the effects of an exit, the transmission of exit status,
zombie processes, signals sent, and so on, see
exit(3).
The function
_exit() is like
exit(3), but does not call any
functions registered with
atexit(3) or
on_exit(3). Open
stdio(3) streams are not flushed. On the other hand,
_exit()
does close open file descriptors, and this may cause an unknown delay, waiting
for pending output to finish. If the delay is undesired, it may be useful to
call functions like
tcflush(3) before calling
_exit(). Whether
any pending I/O is canceled, and which pending I/O may be canceled upon
_exit(), is implementation-dependent.
In glibc up to version 2.3, the
_exit() wrapper function invoked the
kernel system call of the same name. Since glibc 2.3, the wrapper function
invokes
exit_group(2), in order to terminate all of the threads in a
process. (The raw
_exit() system call terminates only the calling
thread.)
execve(2),
exit_group(2),
fork(2),
kill(2),
wait(2),
wait4(2),
waitpid(2),
atexit(3),
exit(3),
on_exit(3),
termios(3)