I have a few Node.js repositories on my computer which I back up daily. In order to have tar exclude the dependencies, I have to place a CACHEDIR.TAG file in each node_modules directory.

The problem is that every time npm install runs it deletes those files. So it was necessary to complicate my script with a pre-backup hook that writes a new tag into each directory.

Today I'm playing around with Rust for the first time. I ran cargo build and looked inside the target folder and saw a CACHEDIR.TAG. I couldn't believe my eyes--it takes care of that by default! This is literally the first time I've seen this implemented in anything.