Are you sure my $days_old = (-M $filename.$file); is correct?

It looks as if you are concatenating the full file name (path + filename) with the filename itself.

When I run your program $days_old never gets any value.

When I use my $days_old = -M $filename; it works.

CountZero

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law