86236bd339
characters are honored. While I'm there also mention posix_spawn in the SEE ALSO section. MFC after: 2 weeks
112 lines
3.1 KiB
Groff
112 lines
3.1 KiB
Groff
.\" 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.
|
|
.\" 3. 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 July 25, 2015
|
|
.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 ,
|
|
.Xr posix_spawn 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn system
|
|
function
|
|
conforms to
|
|
.St -isoC
|
|
and is expected to be
|
|
.St -p1003.2
|
|
compatible.
|
|
.Sh SECURITY CONSIDERATIONS
|
|
The
|
|
.Fn system
|
|
function is easily misused in a manner that enables a malicious
|
|
user to run arbitrary command,
|
|
because all meta-characters supported by
|
|
.Xr sh 1
|
|
would be honored.
|
|
User supplied parameters should always be carefully santized
|
|
before they appear in
|
|
.Fa string.
|