Why Perl programs should always 'use strict'
Yes, every Perl programmer knows that you should 'use strict', but sometimes it's just easier not to. BUT YOU SHOULD ALWAYS DO IT ANYWAY. I just spent an hour debugging a bit of existing code where I added a bit of fork/waitpid code (copy/pasted from elsewhere) to implement concurrent child processing. And because 'use strict' wasn't on in (not my fault, the original code isn't mine), and I didn't add use POSIX ":sys_wait_h";
at the start, the WNOHANG constant wasn't defined. So perl just said "ok, I'll make that 0".