I keep a directory on my home server with all of my important files on it. I want to make offline backups of this directory. But as I add and modify file, I also want to be able to make comparisons between different backups and the current version in a "diff" style. In particular, I want to see which files have been added, which have been deleted, and which have been modified (although it's not important for me to see the file-level diffs).
I know that rsync has this kind of functionality sort-of built into it for doing its job, but it doesn't seem to expose it directly. I also know what I'm looking for is an implementation of a Merkle tree.
Does anyone have any recommendations for lightweight software that can do this kind of directory diff?