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

NAME
       _exit, _Exit - terminate the calling process

SYNOPSIS
       #include <unistd.h>

       noreturn void _exit(int status);

       #include <stdlib.h>

       noreturn 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 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
       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.

       The raw _exit() system call terminates only the calling thread, and actions such as reparenting child processes or sending SIGCHLD to the parent process are per‐
       formed only if this is the last thread in the thread group.

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)

Linux                                                                          2021-03-22                                                                       _EXIT(2)