This is kind of a fun idea - Stuff that yoi did on your computer or computer system (for those of us who have used big iron - including minis) that either seemed good at the time, you wanted to see what happens, or just a glorious oops.
I have one from today - after watching Eric’s video on Regolith, I got the idea to use tmux to monitor some systems from a TTY (where you press ctrl-alt-n with n some number between 1 and 7). I had 4 windows going, with htop, journalctl -f, apt, and a ready command line. Htop was showing Memory was getting high and 100% of the cpu was working. I still was logged on and had Regolith with a browser open and a terminal going. I wanted to kill the gui and see how much cpu and memory was saved. From my one free tmux window, I typed “init 2”.
Oh, my. I’ve never seen a kernal panic that bad before. After the dump, the system went back to running the four tmux windows like nothing happened. I checked the runlevel, and it said 5 3 (5 is the previous runlevel, and 3 was the current). The cpu usage is 0 - 2 % and only 154 meg is being used.
Lesson lerned - the gui is a resource hog and never change runlevels inside of tmux.