Every now and then when previewing Hugo (via hugo serve) as I'm editing it in Emacs I'll get a strange error like:

ERROR 2021/10/18 19:36:03 process: readAndProcessContent: walk:
/home/user/skeptric/content/user@machine.2139:12345 no such file or directory
(setq create-lockfiles nil)
If I got the above error when editing a file called about.md I'd normally be able to find a symlink like .#about.md -> user@machine.2761:12345. This turns out to be emacs system for file locks. The .#<filename> is symlinked to <user>@<host>.<pid>:<time since boot>. Then when another user tries to to open the file in emacs it will then complain about the file being locked. You can turn this off by setting create-lockfiles to nil.