_EXIT(2) BSD System Calls Manual _EXIT(2)
_exit, _Exit -- terminate the calling process
The _exit() and _Exit() functions terminate a process with the following
o All threads in the process are terminated.
o All open file descriptors 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.
o 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 status is set as defined by
wait(2). (Note that typically only the lower 8 bits of status are
passed on to the parent, thus negative values have less meaning.)
o The parent process ID of all of the calling process's existing child
processes are set to 1; the initialization process (see the DEFINI-
TIONS section of intro(2)) inherits each of these processes.
o 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 and SIGCONT sig-
nals are sent to all members of the newly orphaned process group.
o 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
Most C programs call the library routine exit(3), which flushes buffers,
closes streams, unlinks temporary files, etc., and then calls _exit().
_exit() and _Exit() can never return.
fork(2), intro(2), sigaction(2), wait(2), exit(3), sysexits(3)
The _exit() function conform to IEEE Std 1003.1-2008 (``POSIX.1''). The
_Exit() function conforms to ISO/IEC 9899:1999 (``ISO C99'').
An exit() system call first appeared in Version 1 AT&T UNIX. It accepts
the status argument since Version 2 AT&T UNIX. An _exit() variant first
appeared in Version 7 AT&T UNIX. The _Exit() function appeared in
BSD November 30, 2014 BSD