This isn't really answering your question, but I feel it is important to point out something that you're doing.

open(FILE,"$_");
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When you do "$foo", it incurs a slight performance hit. Simply $foo on its own is better. Also, apparently, if $foo happens to be a scalar reference, Perl will dereference it if you don't put it in quotes, but won't otherwise. I doubt you want to open a file named with the memory address of the reference?

See the part of the Perl FAQ that says "What's wrong with always quoting "$vars"?"