1.\" $NetBSD: system.3,v 1.13 2002/07/10 14:37:16 yamt Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" from: @(#)system.3 8.1 (Berkeley) 6/4/93 39.\" 40.Dd June 4, 1993 41.Dt SYSTEM 3 42.Os 43.Sh NAME 44.Nm system 45.Nd pass a command to the shell 46.Sh LIBRARY 47.Lb libc 48.Sh SYNOPSIS 49.Fd #include \*[Lt]stdlib.h\*[Gt] 50.Ft int 51.Fn system "const char *string" 52.Sh DESCRIPTION 53The 54.Fn system 55function 56hands the argument 57.Fa string 58to the command interpreter 59.Xr sh 1 . 60The calling process waits for the shell to finish executing the command, 61ignoring 62.Dv SIGINT 63and 64.Dv SIGQUIT , 65and blocking 66.Dv SIGCHLD . 67.Pp 68If 69.Fa string 70is a 71.Dv NULL 72pointer, 73.Fn system 74will return non-zero. 75Otherwise, 76.Fn system 77returns the termination status of the shell in the format specified by 78.Xr waitpid 2 . 79.Sh RETURN VALUES 80If a child process cannot be created, or the termination status of 81the shell cannot be obtained, 82.Fn system 83returns -1 and sets 84.Va errno 85to indicate the error. 86If execution of the shell fails, 87.Fn system 88returns the termination status for a program that terminates with a call of 89.Fn exit 127 . 90.Sh SEE ALSO 91.Xr sh 1 , 92.Xr execve 2 , 93.Xr waitpid 2 , 94.Xr popen 3 95.Sh STANDARDS 96The 97.Fn system 98function 99conforms to 100.St -ansiC 101and 102.St -p1003.2-92 . 103.Sh CAVEATS 104Never supply the 105.Fn system 106function with a command containing any part of an unsanitized user-supplied 107string. 108Shell meta-characters present will be honored by the 109.Xr sh 1 110command interpreter. 111