That is actually a completly safe command to run (although I would not recomend it). rm by defualt does not allow you to delete '/'. To override this, you want

That is actually a completly safe command to run (although I would not recomend it). rm by defualt does not allow you to delete '/'. To override this, you want sudo rm -rf --no-preserve-root / Regardless, everyone knows that sudo rm -rf / is a bad idea, try using something more cryptic. I reccomend: sudo dd if=/dev/zero of=/dev/sda For those of you thinking "but surely sda is mounted, Linux won't let you write to it", wrong. I just tested this on my machine (using a specially made loop-back device). You can write directly to a mounted device. For those curius, after zero'ing out the device, attempting to 'ls' in the mounted directory resulted in either ls printing "killed" and terminating instantly, or hanging and refusing to respond to ^C.