open $new, "<ncatalog.db" or die;
open $old, "<tmp/ncatalog.db" or die;

while (<$new>) {
    chomp;
    my ($key, $loc) = split /:/;
    $newdb{$key} = $loc;
}
close $new;

while (<$old>) {
    chomp;
    my ($key, $loc) = split /:/;
    if (!defined($newdb{$key})) {
        print "-$key:$loc\n";
    } else {
        if ($newdb{$key} ne $loc) {
            print "#$newdb{$key} <- $key:$loc\n";
        }
        $newdb{$key} = "";
     }
}
close $old;

for my $i (keys %newdb) {
    print "+$newdb{$i}\n" if $newdb{$i} ne "";
}