update: psini has already suggested this.

If you want to allow command words to be abbreviated to uniqueness, something like the following might appeal:

use strict;
use warnings;

my $word = shift;
my @words = qw(lock tubes on raider dispersion offset fire all torpedo
+es);
my $pat = quotemeta($word);
my @matches = grep (/^$pat/, @words);

if(@matches == 0) {
    print "Unknown command \"$word\"\n";
} elsif(@matches == 1) {
    print "Recognized \"$word\" as command $matches[0]\n";
} else {
    print "Ambiguous command \"$word\" could be any of: @matches\n";
}
[download]