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_EXIT(2) Linux Programmer's Manual _EXIT(2)
_exit, _Exit - terminate the calling process
#include <unistd.h>
noreturn void _exit(int status);
#include <stdlib.h>
noreturn 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.
C library/kernel differences
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,
and actions such as reparenting child processes or sending
SIGCHLD to the parent process are performed only if this is the
last thread in the thread group.
execve(2), exit_group(2), fork(2), kill(2), wait(2), wait4(2),
waitpid(2), atexit(3), exit(3), on_exit(3), termios(3)
This page is part of release 5.13 of the Linux man-pages project.
A description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2021-03-22 _EXIT(2)
Pages that refer to this page: clone(2), exit_group(2), fork(2), kill(2), prctl(2), ptrace(2), seccomp(2), setsid(2), shmop(2), syscalls(2), vfork(2), wait(2), atexit(3), daemon(3), exit(3), on_exit(3), pmgetconfig(3), pmnomem(3), system(3), persistent-keyring(7), signal-safety(7), socket(7), user-keyring(7), user-session-keyring(7)
Copyright and license for this manual page
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