#!/usr/bin/perl
use strict;
use warnings;

my $dictionary = 'words.txt';
open(my $fh, '<', $dictionary) or die "Unable to open '$dictionary' for reading: $!";
my %data;
while (<$fh>) {
    chomp $_;
    my $str = join '', sort map lc(), split //;
    push @{$data{$str}}, $str;
}

my $letters = $ARGV[0] or die "Usage: $0 <set_of_letters>";
$letters = join '', sort map lc(), split //, $letters;

if (! exists $data{$letters}) {
    print "Could not find any matching words\n";
}
else {
    for my $word (@{$data{$letters}}) {
        print "$word\n";
    }
}