And if you want to get really evil (read nonportable, and somewhat unreliable) you can sometimes associate the filenum back to a filename. Warning: this code is fragile, won't always work, and will only work on unix. 
my $fileno = fileno($fh);
my $filename = readlink("/dev/fd/" . $fileno);

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See: Re: Re: Can you delete a file by descriptor?

-Blake

In reply to Re3: Storing metadata with file handles by blakem
in thread Storing metadata with file handles by gomez18

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