I am a linux newbie so excuse me if I ask silly things. I recently find out that if I edit GRUB before booting and I add rw init=/bin/bash I end up with a root shell. Being in a condition that I want to understand everything I would like to know why this happens. I mean is it a bug? is it a feature? is it there to help admins to fix things as it only works if you have physical access to a computer? Which part are we exploiting? GRUB or the actual kernel? Sorry for asking a lot of things.