You can simplify your read/write functions:

@output=<FILE>; is equivalent to while(<FILE>) { push @output, $_; }

even better {local undef $/; $output=<FILE>; } slurps the entire file into a string which you can then output by simply printing it

I would also use the ISO standards for date (see Re: (tye)Re: sorting mm/dd/yy) but that's more of a pet peeve of mine.