Back in the day, it was possible to completely trash any ‘nix system by running the recursive delete command in the root partition:
# rm -rf /
There are plenty of stories of system administrators who did something like this (with slight variations, and always by accident) and ended up with a mess.
Today I ran that command on four different servers, on purpose, so I could wipe out everything on them. Imagine my surprise when I ran into a safeguard!
# rm -rf /
rm: it is dangerous to operate recursively on /
rm: use –no-preserve-root to override this failsafe
rm: it is dangerous to operate recursively on /
rm: use –no-preserve-root to override this failsafe
Well, shoot, my operating system is warning me that I shouldn’t be deleting every file on my computer!
It’s funny that someone actually thought of that and added it to the delete command. Of course I forged ahead and added the flag so I could proceed with complete system destruction. Take that!