Do you mean File::Tail?

I can understand not wanting to use a module that isn't core. We'll I can understand why you would think that at least,but in general i would recommend that you use the tools provided if they fit your need. Don't let the fact that something is not core deter you from using it. I won't guess your reasons but i know I've done the same in the past because i thought it was too hard to install modules. I was wrong. ;) If you want to learn to do it yourself go for it! I would check the codings, docs and bugs for File::Tail as a way to learn about it. You can view the code for File::Tail directly on cpan.