crontab: temp file must be edited in place

If you try to add a cron job with crontab -e using Vim, without any configuration, you will probably get this error message:

crontab: temp file must be edited in place

Since Vim is one of, if not the most commonly used $EDITOR, it is a bit surprising that this does not work out of the box. It has to do with the way Vim handles backup files, turning that feature off (only for crontab files) will fix the issue.

TL;DR: put this in your .vim/after/ftplugin/crontab.vim:

setlocal nobackup nowritebackup