From "perldoc IPC::Open3" (the second paragraph):

If WTRFH begins with `<&', then WTRFH will be closed in the parent, and the child will read from it directly. If RDRFH or ERRFH begins with `>&', then the child will send output directly to that filehandle. In both cases, there will be a dup(2) instead of a pipe(2) made.

So you should be able to do what you want simply by change one line to: my $pid = open3("<&STDIN", ">&OUTPUT", ">&ERRLOG", $cmd) or die "$!"; Note that this will close those file handles in the parent as can be seen by this test program which does put the desired output into the specified files:

#!/usr/local/bin/perl

# Script to test IPC::Open3
# Runs, displays $pid to STDOUT, but opened
# files are empty.

use strict;
use warnings;

if( @ARGV ) {
    print STDOUT "StdOut!\n";
    print STDERR "StdErr!\n";
    exit( 0 );
}

#use diagnostics;
use IPC::Open3;

$|++;

my @cmd = ($^X,$0,"Test");

open(ERRLOG, ">error.log") or die "Can't open error log! $!";
open(OUTPUT, ">output.log") or die "Can't open output log! $!";

my $pid = open3("<&STDIN", ">&OUTPUT", ">&ERRLOG", @cmd) or die "$!";

print "PID was $pid\n";

close(ERRLOG) or die "Can't close filehandle! $!";
close(OUTPUT) or die "Can't close filehandle! $!";
defined( my $x= <STDIN> ) or warn "Can't read STDIN: $!\n";
[download]

and then says:

PID was 416
readline() on closed filehandle main::STDIN at open3.pl line 32.
Can't read STDIN: Bad file descriptor
[download]

So you might want to dup STDIN first: open( IN, "<&STDIN" ) or die "...: $!\n"; and pass in "<&IN" instead of "<&STDIN".

        - tye (but my friends call me "Tye")