I occassioanlly need to scan a folder and all of its subdirectories to see if any of them DO NOT contain files of a certain type.
I'm fully aware you can do this with some combination of shell commands, but I always spent 20 minutes googling for how to do it again every time I needed to. It was faster just to write this small utility myself.
I call it
dnc, which stands for "does not contain". You can download the source or a pre-built binary on GitHub. The builds aren't notarized. So be sure to ask Apple if it's OK to run this on your Mac.
Read the full post for an example of why I need this script.