109 lines
3.2 KiB
Groff
109 lines
3.2 KiB
Groff
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.\" $NetBSD: system.3,v 1.17 2008/08/27 06:45:02 christos Exp $
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.\"
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.\" Copyright (c) 1990, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" This code is derived from software contributed to Berkeley by
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.\" the American National Standards Committee X3, on Information
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.\" Processing Systems.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" from: @(#)system.3 8.1 (Berkeley) 6/4/93
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.\"
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.Dd August 2, 2007
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.Dt SYSTEM 3
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.Os
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.Sh NAME
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.Nm system
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.Nd pass a command to the shell
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdlib.h
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.Ft int
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.Fn system "const char *string"
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.Sh DESCRIPTION
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The
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.Fn system
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function
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hands the argument
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.Fa string
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to the command interpreter
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.Xr sh 1 .
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The calling process waits for the shell to finish executing the command,
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ignoring
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.Dv SIGINT
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and
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.Dv SIGQUIT ,
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and blocking
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.Dv SIGCHLD .
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.Pp
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If
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.Fa string
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is a
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.Dv NULL
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pointer,
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.Fn system
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will return non-zero, if the command interpreter is available, or zero if none
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is available.
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Otherwise,
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.Fn system
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returns the termination status of the shell in the format specified by
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.Xr waitpid 2 .
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.Sh RETURN VALUES
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If a child process cannot be created, or the termination status of
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the shell cannot be obtained,
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.Fn system
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returns -1 and sets
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.Va errno
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to indicate the error.
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If execution of the shell fails,
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.Fn system
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returns the termination status for a program that terminates with a call of
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.Fn exit 127 .
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.Sh SEE ALSO
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.Xr sh 1 ,
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.Xr execve 2 ,
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.Xr waitpid 2 ,
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.Xr popen 3 ,
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.Xr shquote 3
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.Sh STANDARDS
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The
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.Fn system
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function
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conforms to
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.St -ansiC
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and
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.St -p1003.2-92 .
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.Sh CAVEATS
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Never supply the
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.Fn system
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function with a command containing any part of an unsanitized user-supplied
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string.
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Shell meta-characters present will be honored by the
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.Xr sh 1
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command interpreter.
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