man_2__exit.txt

_EXIT(2)                           Linux Programmer's Manual                          _EXIT(2)

NAME
       _exit, _Exit - terminate the calling process

SYNOPSIS
       #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

DESCRIPTION
       The  function  _exit() terminates the calling process "immediately".  Any open file de‐
       scriptors belonging to the process are closed.  Any children of the process are  inher‐
       ited  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 using one of the wait(2) family of calls.

       The function _Exit() is equivalent to _exit().

RETURN VALUE
       These functions do not return.

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.  The function _Exit() was introduced by C99.

NOTES
       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 or‐
       der to terminate all of the threads in a process.

SEE ALSO
       execve(2), exit_group(2), fork(2), kill(2), wait(2), wait4(2),  waitpid(2),  atexit(3),
       exit(3), on_exit(3), termios(3)

COLOPHON
       This page is part of release 5.05 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                                     2020-02-09                                  _EXIT(2)