It is not clear and we can't proof it. So I guess someone just writes it for him or not That the example is taken form the Adv. Bash S.G. is nor positive nor negative, just wanted to mention it cause I felt like it.

That he asks for a Perl solution could come of that I wrote in my 2nd post, that there is for sure some handy random function in Perl already:

Since he already might have given up searching for a solution in shell script because no one wrote a solution yet nor he might have found one on the net yet, he just asks for one.
There are people asking for much simpler stuff they could even find with 10 seconds googling, so...
Also there are sometimes much more rude or demanding posts that get answers from the helpful folks so that I personally think if someone has a solution, maybe just post it and it's over.

I'll even write it in perl for him if he can convince me it's not homework. But you learn a lot more from trying yourself (and having your mistakes corrected) than reading other peoples code.

There's lots of "other peoples code" on the web, too