Exactly. You can build rules with ufw and view them on iptables. Maybe the one thing ufw does better out of the box is persistent rules and simpler “firewall on/off” switch, but specially on this particular question I don’t think they matter.
They are excactly what the name implies. Testing is generally pretty good, but it’s still testing. And unstable is also what the name implies. People, myself included back in the day, run both as daily drivers, but if you want rock stable distribution installing unstable revision might not be the best choise.
Debian. I’ve had installations which went trough several major version upgrades, I’ve worked with ‘set and forget’ setups where someone originally installed Debian and I get my hands on it 3-5 years later to upgrade it and it just works. Sure, it might not be as fancy as some alternatives and some things may need manual tweaking here and there, but the thing just works and even on rare occasion something breaks you’ll still have options to fix it assuming you’re comfortable with plain old terminal.
Can you switch to console? Try ctrl+alt+F2 when the system is booted up and log in to that.
I suppose some package update was interrupted or crashed. You can attempt to re-run what’s missing with ‘sudo apt-get install’ and ‘sudo dpkg-reconfigure -a’. And, assuming your console access works, you can at least check log files on what’s wrong, but for that I don’t think any generic ‘read /var/log/syslog’ file is too helpful as there’s a ton of stuff and with things like journalctl it’s pretty difficult to navigate around if you don’t know what you’re looking for.
And also, more details would be helpful. What you mean by ‘enters a loop’, what it actually says that went wrong and so on.
I think it’s easier the other way round, find all symlinks and grep the directory you want to move from results.
Something like ‘find /home/user -type -l -exec ls -l {} ; | grep yourdirectory’ and work from there. I don’t think there’s an easy way to list which symlinks point to any actual file.