Why Does Adding the Docker Repository to APT Sources Mess Up My Sudo Functionality?

It looks like your script involves a recursive copy over the /etc directory. Since that’s where your permission issues arise, I’d advise checking the ownership settings on the source directory you’re using for the copy. Maybe run some "ls -l /etc" commands before and after the copy to see what changes are being made.

I checked out your original post, and one thing to consider is that Docker installation on Raspberry Pi usually advises starting with a clean installation—specifically, one that doesn't have any prior Docker instances. When you installed, did you make sure it was a completely fresh install without any existing Docker leftovers? Also, it sounds like there might be a script running on boot that's altering ownership—check your init scripts to ensure nothing unusual is happening there.

I’ve installed Docker on multiple machines without facing this issue, so something definitely seems off with your setup. Where are you getting Docker from? It might help to outline what steps you've followed and what you think could be going wrong.