This tip shows how to replace a built-in command using :cabbrev to automatically replace the existing command when it is typed. For example, you may want to change the behavior of a built-in command like :e. Or, you may make a common typo, like using :w1 instead of :w!. For whatever reason, if you want to change the behavior of a built-in command, you can't just use :command to override it, because user-defined commands must begin with a capital letter. Suppose you have a user-defined :E command that you want to use to override the default :e command. You could do the following: help ].