Why does Vim save files with a ~ extension?

Question

I've found that while using Vim on Windows Vim saves the file, a .ext.swp file that's deleted on closing the Vim window and a .ext~ file.

I assume the .ext.swp file is a session backup in case Vim crashes. What's the purpose of the .ext~ file however? Is this a permanent backup file? It's annoying as I'd like to copy all the files I'm working on to my host, without these duplicates. How can I turn this off or, if it's there for a good reason, hide the files?

Answer 1

I think the better solution is to place these lines in your vimrc file

set backupdir=~/vimtmp//,.
set directory=~/vimtmp//,.

The first line is for backup files, the second line for swap files. The double slash at the end ensures that there is no conflict in case of two files having the same name, see comments (at the time of this edit this option is only honored for swap files, not yet for backup files). The ,. allow vim to use the current directory if the former doesn't exist.

You have to create a directory in your home directory called vimtmp for this to work. Also, check that backups are enabled in your config (add set backup if not).

That way you get the benefit of both worlds, you don't have to see the files, but if something does get futzed you can go get your backup file from vimtmp. Don't forget to clean the directory out every now and then.