Sidenote based on this–

("how do I add text files to this list?"... answer: make 2 lists & join them.)

–join is a proper operator as well as a concept and it’s definitely not what you want here. push @files, @xml_files, @text_files; or my @files = ( @xml_files, @text_files ); or some variety along those lines is more what you’ll want. You might already know this, I only mention it because of “join them.”