bidir is a little program that examines two files, and copies the newer to the older.
It is suitable for keeping only the latest version of a file that changes on two different
hosts - though it assumes that the files are on "local" filesystems - the author uses
an automounter with sshfs to do the networking part.
I wrote it to replace unison for my usage, because:
Unison does a lot more than what I need.
Unison can be a little brittle:
Unison wants to see the same version of unison on each end of the communication.
It wants unison to be built with the same version of OCaml on each end of the communication.
I'm not sure what else, but fixing the above two "problems" wasn't enough for my usage after an OS upgrade.
bidir is written in Rust and can be downloaded here.