_EXIT(2)



_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
       _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 oper-
       ation).  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().

RETURN VALUE
       These functions do not return.

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.  The function _Exit() was in-
       troduced 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 fin-
       ish.   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 imple-
       mentation-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.)

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

COLOPHON
       This  page  is  part of release 5.07 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)

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