...and then I woke up, had a cuppa coffee, and said to myself: "Hmmm, someone must've already done this. Let's check CPAN!". (When am I going to learn to check CPAN first? I too often find myself writing code, and when I'm 75% of the way done, I then go "D'oh!" and check CPAN, and find what I need. Ah, well, the coding is at least teaching me Perl...)

And I found three modules that would do what you want: File::DirSync, File::Backup and File::Repl. I stopped looking after these three, even though search.cpan.org wanted to give me many more pages...

Another item I stumbled across while looking is File::Set, which might be a useful base if you want to build something a bit more custom.

--roboticus