I use all of the three language in my day-to-day computer usage (i.e. I have scripts in each one of them), and I don't think Python or Ruby really replaces Perl

I use all of the three language in my day-to-day computer usage (i.e. I have scripts in each one of them), and I don't think Python or Ruby really replaces Perl 5 at what it's doing good: being a very powerful Unix citizen. Perl 5 is still better at regexps, at string manipulation, at how it combines these features w/ Unix I/O, and at offline documentation. Ruby has the best syntax and language flexibility among all (I hate Python's significant indentation and general unnecessary "stinginess" of the syntax), and Python shines with its wide array of libraries and availability of jobs. Also, AFAIK Python supports Windows better, and has a better REPL than Ruby (Irb can not run all the code the interpreter itself can run).