# This is cat.pl
$|=1;
while(<>) {
  print;
}
chr(0x1a) if $^O eq 'MSWin32';

##</code><code>##

# This is ls.pl
use strict;
use warnings;
use IPC::Open2;
# OUTPUT: Filehandle for output from cat.pl
# INPUT: Filehandle for input to cat.pl
open2(*OUTPUT,*INPUT,"$^X", "cat.pl") or die "$!";
print INPUT "first line\nsecond line\n";
if ($^O eq 'MSWin32') {
  select INPUT;
  $| = 1;
  print INPUT chr(0x1a);
}
close INPUT;
my @result=<OUTPUT>;
close OUTPUT;
print "RESULT:\n@result\n";

##</code><code>##

perl ls.pl