From Vim Tips Wiki
When Vim is called from
crontab -e it will not work if the '
backup' option is set to no or auto. (I get the error message
crontab: temp file must be edited in place
when exiting Vim.) There is some information at :help crontab but it does not suggest how to fix the problem. So far, adding this to my vimrc file seems to work:
au BufEnter /private/tmp/crontab.* setl backupcopy=yes
The temporary file created by crontab on Mac OS X is named something like
/private/tmp/crontab.XXXXXXXXXX (with a random string of characters at the end). On other systems, you may need to use a different pattern.
Another option that can be set in vimrc tip from ( http://tim.theenchanter.com/2008_07_01_archive.html ) is
You can also create a file ~/.vim/ftplugin/crontab.vim with the following content: