#!/usr/bin/perl

use warnings;
use strict;

open( OUTPUT, '>', '/tmp/output.txt' )
  or die "Error: Cannot open the file - $!\n";

open( my $input, '<', '/tmp/input.txt' )
  or die "Error: Cannot open the  file - $!\n";

print OUTPUT while (<$input>);

close( $input );
close( OUTPUT );