Thank you for taking the time to help me. I just discovered that the Show Invisibles trick no longer works. However, I found another trick that works: I replaced the old file with a new file, created with the latest version of TextWrangler. When I saved it, the dialog box had a drop-down menu for line breaks with the default setting Unix (LF). My guess is that the old file had a different setting for line breaks, but the new default setting is what Perl needed to recognize the input correctly.