"The only way beginners are going to learn is experimenting with the command line, not having their hands held with a a tiny subset of what's available."

    function public_ip() {
      curl -sL myip.dk | egrep '[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}'
    }

Do you seriously think that people should have to type that text mess for the sake of "learning?" In fact, except for the sed and base64 commands, I'd say none of these are anywhere near trivial.