Something else you should consider is that you are opening yourself for a potential attack by allowing the user to supply data that you will feed to system, etc. You really should consider using Safe to scrub the data for things like cat /etc/passwd or rm -rf /. Try running these these two pieces of code on your *nix environment:

# BAD!
perl -E'my $cmd = "@ARGV"; print `$cmd`' cat /etc/passwd
[download]

# BETTER!
perl -MSafe -E'my $c=Safe->new; my $cmd = $c->reval("@ARGV"); print `$
+cmd`' cat /etc/passwd
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)