That's not an error, it's a warning from use warnings;. So now you've got output showing that \v does nothing more than printing a literal 'v', and a warning telling you that \v is an unrecognized escape sequence, which is being passed through. Add to that the comments by myself and others in the forum (on your other thread with the same subject), as well as the POD that I identified, and you've got more than enough indicators telling you that there is no vertical tab identified by "\v" in Perl's string interpolation.