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 & 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 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

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