gistfile1.pl

use strict;
use warnings;
use IPC::Open2 qw(open2);

## warning = Name "main::OUT1" used only once: possible typo 
open2(\*OUT1, undef, 'iostat', '1', '3');
open2(\*OUT2, "<&OUT1", 'cat', '-nu');
print while(<OUT2>);

## error = open2: close(main::GLOB(0x827988)) failed: Bad file descriptor 
my ($out1, $out2);
open2($out1, undef, 'iostat', '1', '3');
open2($out2, "<&$out1", 'cat', '-nu');
print while(<$out2>);