NAME

_Exit, _exit — terminate the calling process

LIBRARY

Standard C Library (libc, -lc)

#include <stdlib.h>

void
_Exit(int status);

#include <unistd.h>

void
_exit(int status);

The _Exit() and _exit() functions are equivalent. They each terminate a process with the following consequences:

All of the descriptors open in the calling process are closed. This may entail delays, for example, waiting for output to drain; a process in this state may not be killed, as it is already dying.
If the parent process of the calling process has an outstanding wait(2) call or catches the SIGCHLD signal, it is notified of the calling process's termination and the status is set as defined by wait(2). (Note that only the least significant 8 bits of status are preserved and returned to the parent via wait(2).)
The parent process-ID of all of the calling process's existing child processes are set to 1; the initialization process (see the DEFINITIONS section of intro(2)) inherits each of these processes.
If the termination of the process causes any process group to become orphaned (usually because the parents of all members of the group have now exited; see “orphaned process group” in intro(2)), and if any member of the orphaned group is stopped, the SIGHUP signal and the SIGCONT signal are sent to all members of the newly-orphaned process group.
If the process is a controlling process (see intro(2)), the SIGHUP signal is sent to the foreground process group of the controlling terminal, and all current access to the controlling terminal is revoked.

Most C programs call the library routine exit(3), which flushes buffers, closes streams, unlinks temporary files, etc., before calling _exit().

_Exit() and _exit() can never return.

The _exit() function conforms to IEEE Std 1003.1-1990 (“POSIX.1”). The _Exit() function conforms to ISO/IEC 9899:1999 (“ISO C99”).