whomst VS atomicxt

I tried to prototype my own implementation of `vidir` in Node.JS a while back (not realizing that it existed under this name in moreutils), and I ended up getting derailed after realizing how incomplete Node.JS's support was for getting the group / username corresponding to a G/UID: https://github.com/stuartpb/whomst

mv can't, or, more correctly the rename system call can not.

rename is an atomic operation from any modern filesystem's perspective, you're not writing new data, you're simply changing the name of the existing file, it either succeeds or fails.

Keep in mind that if you're doing this, mv (the command line tool) as opposed to the `rename` system call, falls back to copying if the source and destination files are on different filesystems since you can not really mv a file across filesystems!

In order to have truly atomic writes you need to:

open a new file on the same filesystem as your destination file

write contents

call fsync

call rename

call sync (if you care about the file rename itself never being reverted).

This is some very naive golang code (from when I barely new golang) for doing this which has been running in production since I wrote it without a single issue: https://github.com/AdamJacobMuller/atomicxt/blob/master/file...