There's a pretty undocumented issue with the [Vim editor](https://www.vim.org/)
which affects files containing extended attributes (xattrs).

Vim may **overwrite** files instead of updating them. In addition to creating
some trouble with inotify watcher and events, this process also clobbers the
extended attributes of a file. This can be problematic if you happen to store
information within the files's `xattrs`. For example, I store an MD5 hash in
some of my articles; when I edit an article, the actual checksum will differ
from the one in xattr, and my Perl script will know to update the article on
this website.

This tendency of Vim is controlled by the `backupcopy` variable. By default,
`backupcopy=yes` for Unix and `backupcopy=auto` otherwise. Some distributions
will unset `backupcopy`, so it may be necessary to put the following in your
`.vimrc` file:

```
set backupcopy=yes
```

Now extended attributes should be preserved across writes. To test this, do the
following in a shell:

```
touch test-file
setfattr -n user.attr1 -v v1 test-file
vim test-file # Add some text and :wq
getfattr test-file
```

Although some claim that this slows down the `:w` command, I've not seen a
measurable difference in performance since using this setting.