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.\"     @(#)_exit.2	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: head/lib/libc/sys/_exit.2 165903 2007-01-09 00:28:16Z imp $
.\"
.Dd June 4, 1993
.Dt EXIT 2
.Os
.Sh NAME
.Nm _exit
.Nd terminate the calling process
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft void
.Fn _exit "int status"
.Sh DESCRIPTION
The
.Fn _exit
system call
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 2
call
or catches the
.Dv SIGCHLD
signal,
it is notified of the calling process's termination and
the
.Fa status
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
inherits each of these processes
(see
.Xr init 8
and the
.Sx DEFINITIONS
section of
.Xr intro 2 ) .
.It
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
.Dq orphaned process group
in
.Xr intro 2 ) ,
and if any member of the orphaned group is stopped,
the
.Dv SIGHUP
signal and the
.Dv SIGCONT
signal are sent to all members of the newly-orphaned process group.
.It
If the process is a controlling process (see
.Xr intro 2 ) ,
the
.Dv SIGHUP
signal is sent to the foreground process group of the controlling terminal,
and all current access to the controlling terminal is revoked.
.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 VALUES
The
.Fn _exit
system call
can never return.
.Sh SEE ALSO
.Xr fork 2 ,
.Xr sigaction 2 ,
.Xr wait 2 ,
.Xr exit 3 ,
.Xr init 8
.Sh STANDARDS
The
.Fn _exit
system call is expected to conform to
.St -p1003.1-90 .
.Sh HISTORY
The
.Fn _exit
function appeared in
.At v7 .