freebsd-dev/lib/libc/stdlib/system.3
James Raynard b487e9d356 Submitted by: (based on code in "Advanced Programming in the Unix Environment"
by W.Richard Ste vens. EINTR handling suggested by bde@freebsd.org).

Code cleanup:

1. Add missing return type.
2. Replace 'union wait' by int.
3. Use Posix-style signal handling instead of signal().
4. Use fork() instead of deprecated vfork().
5. Block signals before fork()'ing, instead of after.
6. Return -1 if fork() fails, instead of 0.
7. Add EINTR handling for waitpid() call.

Also add claim of Posix conformance to man page.
1996-06-05 00:08:54 +00:00

97 lines
2.9 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.
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.\" @(#)system.3 8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt SYSTEM 3
.Os
.Sh NAME
.Nm system
.Nd pass a command to the shell
.Sh SYNOPSIS
.Fd #include <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.
.Pp
The
.Fn system
function
returns the exit status of the shell, or \-1 if the
.Xr wait 2
for the shell failed.
A return value of 127 means the execution of the shell
failed.
.Sh SEE ALSO
.Xr sh 1 ,
.Xr execve 2 ,
.Xr wait 2 ,
.Xr popen 3
.Sh STANDARDS
The
.Fn system
function
conforms to
.St -ansiC .
and is expected to be
.St -p1003.2
compatible.