Foxhole

I heard there's something in PHP that few developers know about (or if they do, they pretend not to or don't care at all) which is a second equality operator that, unlike the simple one, doesn't lie to you.

Once you're in as a low-privilege user, don't assume you need full sudo rights to reach root. Check exactly which commands you're allowed to run with elevated privileges — sometimes it's just one, and that's enough. A surprising number of common Linux utilities can be abused to write files as root, even if you can't run arbitrary commands directly. Think about what a program that writes text to files could let you create or modify if it runs with root's permissions.