Would chomp help you here? It will happily consume/read your file on a line-by-line basis, thereby allowing you to run a RE (regex) comprised of your users input against your file.

That's probably how I'd approach it, anyway. :)

HTH, and best wishes.

--Chris

#!/usr/bin/perl -Tw
use Perl::Always or die;
my $perl_version = (5.12.5);
print $perl_version;