Mastering Vim

A word about swap files

By default, Vim keeps track of the changes you make to files in swap files. The swap files are created as you edit the files, and are used to recover the contents of your files in case either Vim, your SSH session, or your machine crashes. If you don't exit Vim cleanly, you'll be greeted by the following screen:

You can either hit r to recover the swap file contents, or d to delete the swap file and dismiss the changes. If you decide to recover the swap file, you can prevent the same message from showing up next time you open the file in Vim by reopening a file and running :e, and pressing d to delete the swap file. ...