I had posted a question on sys.unix.wizards about this a long long time ago when in academia. The gist of it was: “when does the system die after issuing the lethal command?”

We tested on a limited number of systems (Linux with kernel around 1.0, SunOS 4.1.4, SGI Irix and both DEC OSF/1 and Ultrix) but I lost the results :(