While working in command prompt, I accidentally typed following command: sudo apt-get install python3- and ubuntu started removing python3 and everything depends on it (including firefox and much more). Fortunately I closed that terminal immediately and reverted everything by checking dpkg log file, but I was wondering why an install command should act like remove? Is it a bug? Consider the situation that you are looking for a package name (pressing Tab twice) and going through possibilities by pressing Enter key and those Enter keys remain in the keyboard buffer and.... youhaaaa... apt-get is removing the entire installation in front of your eyes.