Over the years I ran into the same issue again and again, that I found some old files on a hard drive or a directory with files somewhere on a machine and I didn’t remember its purpose or the state it was in.

For source code git solves this problem in a neat fashion, but you wouldn’t typically commit binaries, PSD, large amounts of JPEGs, RAW images or even Video files. I had always longed for a quick and easy way to check the difference between two folders.

Last month on a long train ride I tried whether AI could help me solve this with shell scripts and readily available UNIX tools¹. And the initial version did work, but was awfully slow (we’re talking dozens of minutes). And since I wanted to dabble in Rust for quite a while now but have never gotten around to it, I tried vibe coding the thing with Claude.

Claude came back with 3 simple files² that compiled and run without error and now run the same thing that took 20 minutes earlier with the shell script in 34 seconds! This definitely goes into my $HOME/bin dir.

I cleaned it up and put it on GitHub. As of now I consider it feature complete, and I have successfully tested it on Linux and macOS.

Considerations

The program uses SHA256 because that is safe and future-proof enough, available just about everywhere and in most cases even hardware-accelerated.

When hashing a directory, it will create a sorted listing of its contents, where each of the entries contains its type, name and hash. This makes this safe and comparable.

To drill into directories further the -v command can be used to show the hashes of the entries.