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[dragonfly.git] / lib / libc / stdlib / system.3
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1.\" Copyright (c) 1990, 1991, 1993
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" This code is derived from software contributed to Berkeley by
5.\" the American National Standards Committee X3, on Information
6.\" Processing Systems.
7.\"
8.\" Redistribution and use in source and binary forms, with or without
9.\" modification, are permitted provided that the following conditions
10.\" are met:
11.\" 1. Redistributions of source code must retain the above copyright
12.\" notice, this list of conditions and the following disclaimer.
13.\" 2. Redistributions in binary form must reproduce the above copyright
14.\" notice, this list of conditions and the following disclaimer in the
15.\" documentation and/or other materials provided with the distribution.
dc71b7ab 16.\" 3. Neither the name of the University nor the names of its contributors
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17.\" may be used to endorse or promote products derived from this software
18.\" without specific prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30.\" SUCH DAMAGE.
31.\"
32.\" @(#)system.3 8.1 (Berkeley) 6/4/93
5d0641a4 33.\" $FreeBSD: src/lib/libc/stdlib/system.3,v 1.13 2008/06/26 08:24:59 danger Exp $
1de703da 34.\" $DragonFly: src/lib/libc/stdlib/system.3,v 1.2 2003/06/17 04:26:46 dillon Exp $
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35.\"
36.Dd June 4, 1993
37.Dt SYSTEM 3
38.Os
39.Sh NAME
40.Nm system
41.Nd pass a command to the shell
42.Sh LIBRARY
43.Lb libc
44.Sh SYNOPSIS
45.In stdlib.h
46.Ft int
47.Fn system "const char *string"
48.Sh DESCRIPTION
49The
50.Fn system
51function
52hands the argument
53.Fa string
54to the command interpreter
55.Xr sh 1 .
56The calling process waits for the shell
57to finish executing the command,
58ignoring
59.Dv SIGINT
60and
61.Dv SIGQUIT ,
62and blocking
63.Dv SIGCHLD .
64.Pp
65If
66.Fa string
67is a
68.Dv NULL
69pointer,
70.Fn system
71will return non-zero if the command interpreter
72.Xr sh 1
73is available, and zero if it is not.
5d0641a4 74.Sh RETURN VALUES
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75The
76.Fn system
77function
78returns the exit status of the shell as returned by
79.Xr waitpid 2 ,
80or \-1 if an error occurred when invoking
81.Xr fork 2
82or
83.Xr waitpid 2 .
84A return value of 127 means the execution of the shell
85failed.
86.Sh SEE ALSO
87.Xr sh 1 ,
88.Xr execve 2 ,
89.Xr fork 2 ,
90.Xr waitpid 2 ,
91.Xr popen 3
92.Sh STANDARDS
93The
94.Fn system
95function
96conforms to
5d0641a4 97.St -isoC
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98and is expected to be
99.St -p1003.2
100compatible.