Learning GNU Emacs, Second Edition

Stopping Commands and Undoing Changes

Sometimes you start a command by accident or change your mind about it. Don’t worry: with Emacs, you can quit in the middle or undo it.

Stopping Commands

When you want to stop any command that’s in progress, press C-g. The word Quit appears in the command area.

Undoing Changes

What happens if you make a mistake while you’re editing? You can undo your changes by pressing C-x u, C-_, or C-/ (for undo) or selecting Undo from the Edit menu. By typing C-x u repeatedly, you can gradually work your way back to a point before your mistake. Although the undo command is very powerful, saving your file frequently, if not compulsively, is nevertheless a good idea. We usually save a file whenever we stop typing—even if only for a few seconds. Train your fingers to press C-x C-s whenever you pause; it’s a good habit to form.

What if you’d like to redo a command after you type undo? There is no formal redo command, but you can use undo in the following way. Just move the cursor in any direction, and type C-x u again. Emacs redoes the last command you undid. You can repeat it to redo previous undos.

Although undo is an important command, it can be slow if you want to undo a large number of changes. Table 2-7 summarizes three methods for undoing changes and circumstances in which you might want to use them.

Table 3-7. Methods for Undoing Changes

If you	Use this command
Don’t like the recent changes you’ve made and want to undo them one by one