% cat myfile.txt | myprogram.pl

##</code><code>##

% myprogram.pl < myfile.txt

##</code><code>##

#!/usr/bin/perl -w

use strict;

my $stream;

while (<>) {
  $stream .= $_;
}

print "Do you want to process the stream?";
my $ans = <STDIN>;

#...
exit;