.TH FDRUN 2
.SH NAME
fdrun \-
run a shell command with I/O redirection.
.SH SYNOPSIS
.EX
include "sys.m";
include "draw.m";
include "fdrun.m";
fdrun := load FDrun FDrun->PATH;

init: fn();
run: fn(ctxt: ref Draw->Context, argv: list of string,
	spec: string, sfds: array of ref Sys->FD, result: chan of string): int;
.EE
.SH DESCRIPTION
.B FDrun
runs a
.IR sh (1)
command, redirecting some of its file descriptors
to user-specified files.
.B Init
must be called first, to initialise the module.
.B Run
invokes the command given by
.I argv
(the first element being the name of the command)
using the graphics context
.IR ctxt .
.I Spec
specifies the redirections that should take place,
each character specifying the redirection for a
particular file descriptor (\f5spec[\fIi\fP]\fR gives
the specification for file descriptor
.IR i ).
If the character is a decimal digit, say
.IR d ,
the file is redirected to
.IR sfds [ d ];
if it is the character
.BR x ,
it is redirected to
.BR /dev/null ;
if the character is a hyphen (\f5-\fP),
no redirection will take place.
.PP
.B Run
returns without waiting for the
command to finish (it returns -1
if the specification was invalid). When
the command has terminated, its exit
status will be sent on
.IR result .
.SH EXAMPLE
Compile a Limbo program and save any errors or warnings:
.EX
fdrun := load FDrun FDrun->PATH;
fdrun->init();
sys->pipe(p := array[2] of ref Sys->FD);
result := chan of string;
fdrun->run(nil, "limbo"::"-gw"::"myfile.b"::nil, "x00", array[] of {p[1]}, result);
efd := p[0];
p = nil;
\&... read any output from efd until EOF
r := <-result;
if(r != nil)
	sys->print("compilation failed (%s)\n", r);
.EE
.SH SOURCE
.B /appl/lib/fdrun.b
.SH SEE ALSO
.IR sh (1),
.IR sh (2)