I got

perl -c "labmonkey.pl"
Scalar found where operator expected at labmonkey.pl line 34, near "--
$allprefixes"
        (Missing operator before  $allprefixes?)
syntax error at labmonkey.pl line 34, near "-- $allprefixes"
labmonkey.pl had compilation errors.
[download]

When I ran your code.

I noticed that you didn't start the code with a 'shebang' line. May I suggest adding these lines to the top of your code:

#! /usr/local/bin/perl
use strict;
use warnings;
[download]

The shebang lets your OS get a clue about what language to expect; strict and warnings will give you a heads up about common mistakes and errors. ('variable used once, possible typo?' is one of my favorites -- I am a three fingered typist, all three fingers are on my left hand. I see that one a lot.)

Welcome to the Monastery, have fun with the Toys, don't forget to enjoy yourself.