bsd man page for _exit

_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 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 & 0377 is returned to the parent process as the process's exit status, and can be collected using one of the wait(2) fam-
       ily 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 order 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 4.15 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								    2017-05-03								  _EXIT(2)