After becoming frustrated with seeing Nautilus appear when I had set Nemo as the file manager, I decided to uninstall nautilus from Zorin OS 16:
sudo apt uninstall nautilus
Then, as I watched all the other stuff get nuked I thought to myself, I better reboot, so I link the action to the outcome which was coming to me: Now I see a black and white terminal login. Running startx does not work. Running lxsession does not work. Then I had an idea: run /usr/bin/gnome-session this seems to pause and then return to terminal doing nothing. Takes about 2 seconds to do this.
Oddly I can't ssh in anymore. Going to the machine ssh isn't running. I reinstall it openssh-server. From another machine I notice the machine's key has changed / regenerated. Odd.
sudo apt install gnome-session
This does something.
But still nothing.
About to following the instructtions at How to remove nautilus without screwing up unity? - Ask Ubuntu but then I realised it is from December 2015 and maybe I should post in the Zorin forum be a little more relevant me thinks.
So... any ideas my next step? Most likely I have a snapshot as the system is on btrfs however I think I'm only on weekly backups which would be sub-optimal solution.
- fix it somehow?
- revert to snapshot? (likely!)
- reinstall Zorin OS? (prefer not)
UPDATE I so restored system using timeshift back 15 days to Sept 29 2021. After updating various apps, I was back in action in only about 5 hours. Amazingly how many updates happen in 15 days. Still though, it would almost be worth patching apt with a warning about uninstalling nautilus but I guess I should be more careful.