.nfs0000... files keep showing up and disappearing when using Mercurial

Question

As of late, something seems to have happened on my machine that is more annoying than anything else: every time I look in a directory for Mercurial changes it tells me about two .nfs#### files that then immediately vanish. #### seems to increment every time they flicker back.

Is my computer going nuts? Is this Mercurial related? File system related (this is a network mounted drive)?

$ hg st
? .nfs000000001b1d062600000a43
? .nfs000000001b1d085a00000a44
$ ls -lhtrA
total 1.7M
drwxrwxr-x 5 nick    nick    4.0K Sep  2 14:34 media/
drwxrwxr-x 6 nick    nick    4.0K Sep 19 17:07 venv/
drwxrwxr-x 7 nick    nick    4.0K Sep 19 18:55 lab_web/
drwxrwxr-x 8 nick    nick    4.0K Sep 19 20:15 templates/
drwxrwxr-x 5 nick    nick    4.0K Sep 20 17:44 .hg/
-rw-rw-r-- 1 nick    nick     252 Jul 23 17:21 manage.py
-rw-rw-r-- 1 nick    nick     177 Sep 19 17:07 requirements.txt
-rw-r--r-- 1 nick    nick    1.7M Sep 19 19:46 lab_sqlite3.db
-rw-rw-r-- 1 nick    nick     141 Sep 19 20:26 debug_requirements.txt
-rw-rw-r-- 1 nick    nick     274 Sep 20 17:44 .hgignore
$ hg st
? .nfs000000001b1d062600000a47
? .nfs000000001b1d085a00000a48
$ hg st
? .nfs000000001b1d062600000a49
? .nfs000000001b1d085a00000a4a

Solution

.nfs* files are related to NFS. They appear on an NFS server when a file is deleted, but is still open by a client. The server must not delete the file because it still needs to provide the data to the clients that have it open. On the other hand, the server must delete the file because the process that deleted it expects it to no longer exist. So the NFS server renames the file to a name that hopefully nobody cares about.

It's no use to try deleting them: you'd be deleting a file that's still open by an NFS client, so the server would only create a new .nfs* file to keep the data.

Eventually the client will close the files and the .nfs* droppings will vanish.

You can instruct Mercurial to ignore those files. In the [ui] section of your ~/.hgrc, add the line ignore = ~/.hgignore.global, and create the file ~/.hgignore.global containing the line .nfs*.