Are you looking to get a bunch of "NO" responses? If so, you should just use arrays instead of hashes. As the code is currently written, you never use the "hash-iness" of %file_list and %build_file, and you might as well replace them both with arrays.

If you are looking to only print out lines that are in both files, then you should read one file into a hash and the other into an array, then code something like this:

foreach (@myArray) {
     print "$_\n" if ($myHash{$_});
}
[download]

Hope this helps.

-Ton
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Be bloody, bold, and resolute; laugh to scorn
The power of man...