As mentioned, give an example INPUT and OUTPUT rather than just the script as we obviously aren't understanding what you want. If all you're looking for is whether or not it's letters, that's what isalpha is for. If you want to know if there is data, use if ($1-) { } or just if ($1) { } . But without an actual example of input and what you expect the output to be, no one seems to know what you want.
