usr/src/lib/libc/sys/_exit.2

.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)_exit.2     6.5 (Berkeley) %G%
.\"
.Dt EXIT 2
.Dd
.Os BSD 4
.Sh NAME
.Nm _exit
.Nd terminate the calling process
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft void volatile
.Fn _exit "int status"
.Sh DESCRIPTION
The
.Fn _exit
function
terminates a process with the following consequences:
.Bl -bullet
.It
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.
.It
If the parent process of the calling process has an outstanding
.Xr wait
call
or is interested in the
.Dv SIGCHLD
signal,
it is notified of the calling process's termination and
the
.Em status
area is set as defined by
.Xr wait 2 .
.It
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
.Xr intro 2 )
inherits each of these processes.
Any stopped children are restarted with a hangup signal
.Pq Dv SIGHUP .
.El
.Pp
Most C programs call the library routine
.Xr exit 3 ,
which flushes buffers, closes streams, unlinks temporary files, etc.,
before
calling
.Fn _exit .
.Sh RETURN VALUE
.Fn _exit
can never return.
.Sh SEE ALSO
.Xr fork 2 ,
.Xr sigvec 2 ,
.Xr wait 2 ,
.Xr exit 3
.Sh HISTORY
An
.Nm exit
function call appeared in Version 6 AT&T UNIX.