Instead of trying once again to re-invent the wheel, just search CPAN for any one of literally hundreds of modules which are "job runners" or "task runners" or "task schedulers" or what-have-you. The thing that you contemplate doing has already been done to death, such that you need not write anything "from scratch," yourself. "Do not do a thing already done ..."
Comment on Re: Yet another spawn question. Portable method?
Excellent advice. I don't know how many articles, notes, posts etc I've looked at that show how to do this and not a single one of them meet my primary goal: run on any platform without modification.
I wrote a sub that runs anywhere and picks the proper system (...) version. Not pretty but it does meet requirements. If anyone wants it, ask.