Looking at the examples given surprise me one thing: just one of the samples gave me this "BEGIN" and "END" (the one provided through the perlmod).

I've read now one article about this thing called BEGIN and it says on one comment:

"You didn't mention that BEGIN blocks even run when syntax checking with perl -cw. That's always seemed worrying on a security basis to me - I'm checking the syntax of the program, not running it! What if the BEGIN block does system( "rm -rf ...")?"

So trust on code that has this feature is a bit dangerous when you want to just syntax check...

For the curiosity I've checked if the library that I'm using to learn perl use this feature and it doesn't! (see here).