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

       _exit, _Exit - terminate the calling process

       #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)):

           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

       _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().

       These functions do not return.

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

       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

   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

       execve(2), exit_group(2), fork(2), kill(2), wait(2), wait4(2),
       waitpid(2), atexit(3), exit(3), on_exit(3), termios(3)

       This page is part of release 5.11 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                              2021-03-22                           _EXIT(2)