Not related to your question, but when you use $filename_pattern = "Remedy.csv" and then /$filename_pattern/, that period character is used as the regex special character (like using [^\n]), which may match more than you intend (eg, it matches "Remedy_csv"). If you want to match strings in which that string occurs literally, quote it (like /\Q$filename_pattern\E/ or with quotemeta). However, I suspect you really want equality: $_ eq $filename_pattern;, or maybe case-insensitive equality (eg, for Windows): lc $_ eq lc $filename_pattern.