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.\"     @(#)system.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/stdlib/system.3,v 1.13 2008/06/26 08:24:59 danger Exp $
.\"
.Dd June 4, 1993
.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
.Sh STANDARDS
The
.Fn system
function
conforms to
.St -isoC
and is expected to be
.St -p1003.2
compatible.