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. 16.\" 3. Neither the name of the University nor the names of its contributors 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 33.\" $FreeBSD: src/lib/libc/stdlib/system.3,v 1.13 2008/06/26 08:24:59 danger Exp $ 34.\" $DragonFly: src/lib/libc/stdlib/system.3,v 1.2 2003/06/17 04:26:46 dillon Exp $ 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. 74.Sh RETURN VALUES 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 97.St -isoC 98and is expected to be 99.St -p1003.2 100compatible. 101