If you're only going to be running this a few times, you could slurp the entire file into memory (such as: local $/; my $data = <FH>), use s/// to get rid of the chars at the end, and write the data back to the file.

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I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident.
-- Schemer

Note: All code is untested, unless otherwise stated