freebsd-skq/lib/libc/stdlib/system.3

.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)system.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd June 4, 1993
.Dt SYSTEM 3
.Os
.Sh NAME
.Nm system
.Nd pass a command to the shell
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fn system "const char *string"
.Sh DESCRIPTION
The
.Fn system
function
hands the argument
.Fa string
to the command interpreter
.Xr sh 1 .
The calling process waits for the shell
to finish executing the command,
ignoring
.Dv SIGINT
and
.Dv SIGQUIT ,
and blocking
.Dv SIGCHLD .
.Pp
If
.Fa string
is a
.Dv NULL
pointer,
.Fn system
will return non-zero if the command interpreter
.Xr sh 1
is available, and zero if it is not.
.Sh RETURN VALUES
The
.Fn system
function
returns the exit status of the shell as returned by
.Xr waitpid 2 ,
or \-1 if an error occurred when invoking
.Xr fork 2
or
.Xr waitpid 2 .
A return value of 127 means the execution of the shell
failed.
.Sh SEE ALSO
.Xr sh 1 ,
.Xr execve 2 ,
.Xr fork 2 ,
.Xr waitpid 2 ,
.Xr popen 3
.Sh STANDARDS
The
.Fn system
function
conforms to
.St -isoC
and is expected to be
.St -p1003.2
compatible.
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" Copyright (c) 1990, 1991, 1993`
			`.\" The Regents of the University of California. All rights reserved.`
			`.\"`
			`.\" This code is derived from software contributed to Berkeley by`
			`.\" the American National Standards Committee X3, on Information`
			`.\" Processing Systems.`
			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. Redistributions in binary form must reproduce the above copyright`
			`.\" notice, this list of conditions and the following disclaimer in the`
			`.\" documentation and/or other materials provided with the distribution.`
			`.\" 4. Neither the name of the University nor the names of its contributors`
			`.\" may be used to endorse or promote products derived from this software`
			`.\" without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
			`.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
			`.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
			`.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE`
			`.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
			`.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS`
			`.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)`
			`.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT`
			`.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY`
			`.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF`
			`.\" SUCH DAMAGE.`
			`.\"`
			`.\" @(#)system.3 8.1 (Berkeley) 6/4/93`
$Id$ -> $FreeBSD$ 1999-08-28 00:22:10 +00:00			`.\" $FreeBSD$`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\"`
			`.Dd June 4, 1993`
			`.Dt SYSTEM 3`
			`.Os`
			`.Sh NAME`
			`.Nm system`
			`.Nd pass a command to the shell`
Introduce ".Lb" macro to libc manpages. More libraries manpages updates following. 2000-04-21 09:42:15 +00:00			`.Sh LIBRARY`
			`.Lb libc`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SYNOPSIS`
Move to using .In instead of .Fd #include <> for include mark-up. Inspired by comment from: dd 2001-09-07 14:46:36 +00:00			`.In stdlib.h`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Ft int`
			`.Fn system "const char *string"`
			`.Sh DESCRIPTION`
			`The`
			`.Fn system`
			`function`
			`hands the argument`
			`.Fa string`
			`to the command interpreter`
			`.Xr sh 1 .`
			`The calling process waits for the shell`
			`to finish executing the command,`
			`ignoring`
			`.Dv SIGINT`
			`and`
			`.Dv SIGQUIT ,`
			`and blocking`
			`.Dv SIGCHLD .`
			`.Pp`
			`If`
			`.Fa string`
			`is a`
			`.Dv NULL`
			`pointer,`
			`.Fn system`
			`will return non-zero if the command interpreter`
			`.Xr sh 1`
			`is available, and zero if it is not.`
Mark the section describing return values with an appropriate section flag. PR: docs/122818 MFC after: 3 days 2008-06-26 08:24:59 +00:00			`.Sh RETURN VALUES`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`The`
			`.Fn system`
			`function`
Clarify format of exit status code. Note when a return code of -1 can be expected. PR: docs/9701 Submitted by: Marc van Kempen <marc@bowtie.nl> 1999-01-27 03:54:09 +00:00			`returns the exit status of the shell as returned by`
			`.Xr waitpid 2 ,`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`or \-1 if an error occurred when invoking`
Clarify format of exit status code. Note when a return code of -1 can be expected. PR: docs/9701 Submitted by: Marc van Kempen <marc@bowtie.nl> 1999-01-27 03:54:09 +00:00			`.Xr fork 2`
Remove whitespace at EOL. 2001-07-15 07:53:42 +00:00			`or`
Clarify format of exit status code. Note when a return code of -1 can be expected. PR: docs/9701 Submitted by: Marc van Kempen <marc@bowtie.nl> 1999-01-27 03:54:09 +00:00			`.Xr waitpid 2 .`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`A return value of 127 means the execution of the shell`
			`failed.`
			`.Sh SEE ALSO`
			`.Xr sh 1 ,`
			`.Xr execve 2 ,`
Clarify format of exit status code. Note when a return code of -1 can be expected. PR: docs/9701 Submitted by: Marc van Kempen <marc@bowtie.nl> 1999-01-27 03:54:09 +00:00			`.Xr fork 2 ,`
			`.Xr waitpid 2 ,`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Xr popen 3`
			`.Sh STANDARDS`
			`The`
			`.Fn system`
			`function`
			`conforms to`
Remove spurious period. 2002-05-27 03:45:27 +00:00			`.St -isoC`
Submitted by: (based on code in "Advanced Programming in the Unix Environment" by W.Richard Ste vens. EINTR handling suggested by bde@freebsd.org). Code cleanup: 1. Add missing return type. 2. Replace 'union wait' by int. 3. Use Posix-style signal handling instead of signal(). 4. Use fork() instead of deprecated vfork(). 5. Block signals before fork()'ing, instead of after. 6. Return -1 if fork() fails, instead of 0. 7. Add EINTR handling for waitpid() call. Also add claim of Posix conformance to man page. 1996-06-05 00:08:54 +00:00			`and is expected to be`
			`.St -p1003.2`
			`compatible.`