Persistent undo history in Vim

Thursday, July 26th, 2012

Once you quit Vim, the undo history for that file is gone. This sometimes gives me problems if I accidentally made a change in a file without knowing it. This usually happens due to a bad Vim command which, for instance, capitalized a single letter.

There’s an option which allows you to make the undo history persistent between Vim sessions. That means you can still undo changes you made in a file, even if you’ve quit Vim in the meantime.

You can add the following to your .vimrc to enable it:

set undofile   " Maintain undo history between sessions

This will create undo files all over the place, which look like this:

-rw-r--r-- 1 fboender fboender 320 2012-07-26 10:23 bad_gateway.txt
-rw-r--r-- 1 fboender fboender 523 2012-07-24 14:51 .bad_gateway.txt.un~

You can remedy this by including the following option in your configuration:

set undodir=~/.vim/undodir

Make sure to create the undodir:

$ mkdir ~/.vim/undodir

The undo files will now be saved in the undodir:

$ ls -la .vim/undodir/
total 12
drwxr-xr-x  2 fboender fboender 4096 2012-07-26 10:32 .
drwxr-xr-x 12 fboender fboender 4096 2012-07-26 10:24 ..
-rw-r--r--  1 fboender fboender  519 2012-07-26 10:32 %home%fboender%bad_gateway.txt

Edit: Thanks to Daid Kahl for pointing out the mistake in the comment after the command.