On Thu, Apr 20, 2017 at 12:07:28AM +0200, Steffen Nurpmeso wrote: > Hmm. Kurt Shoens added # as a null() saying "The do nothing > command for comments." before that (2BSD, file copyright 1979). Is it possible that you were looking at 2BSD/src/Mail/cmd3.c? 2BSD is an add-on for V6, without any Bourne shell.