Over the past six months, I’d copied a set of files down from a network drive, then new ones were added to the network drive, and I’d copied some of the new ones down but maybe not all? How could I possibly clean up this mess?

Easily, it turns out!

$ diff -srq /mnt/Volumes/2023/Bank_Statements/ /local/receipts/2023/

This will list all the files, and mark if they’re only in the /mnt/Volumes/2023/Bank_Statements/ directory, only in the /local/receipts/2023/ directory, if the file exists in both places but is different, or if the file exists in both places and is identical. The -s flag means “report identical files,” the -r flag is to go recursively, and the -q flag just announces the files are the same/different rather than showing their differences.

This’ll work as long as the file names have not been changed. If file names have changed, it’ll require a more robust utility.