_Exit(2) — Linux manual page


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

NAME         top

       _exit, _Exit - terminate the calling process

SYNOPSIS         top

       #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)):

           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

DESCRIPTION         top

       _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().

RETURN VALUE         top

       These functions do not return.

CONFORMING TO         top

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

NOTES         top

       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.)

SEE ALSO         top

       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         top

       This page is part of release 5.09 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

Linux                            2020-02-09                         _EXIT(2)

Pages that refer to this page: signal-safety(7)