Tinkering is all fun and games, until it's 4 am, your vision is blurry, and thinking straight becomes a non-option, or perhaps you just get overly confident, type something and press enter before considering the consequences of the command you're about to execute... And then all you have is a kernel panic and one thought bouncing in your head: "damn, what did I expect to happen?".
Off the top of my head I remember 2 of those. Both happened a while ago, so I don't remember all the details, unfortunately.
For the warmup, removing PAM. I was trying to convert my artix install to a regular arch without reinstalling everything. Should be kinda simple: change repos, install systemd, uninstall dinit and it's units, profit. Yet after doing just that I was left with some PAM errors... So, I Rdd-ed libpam instead of just using --overwrite. Needless to say, I had to search for live usb yet again.
And the one at least I find quite funny. After about a year of using arch I was considering myself a confident enough user, and it so happened that I wanted to install smth that was packaged for debian. A reasonable person would, perhaps, write a pkgbuild that would unpack the .deb and install it's contents properly along with all the necessary dependencies. But not me, I installed dpkg. The package refused to either work or install complaining that the version of glibc was incorrect... So, I installed glibc from Debian's repos. After a few seconds my poor PC probably spent staring in disbelief at the sheer stupidity of the meatbag behind the keyboard, I was met with a reboot, a kernel panic, and a need to find another PC to flash an archiso to a flash drive ('cause ofc I didn't have one at the time).
Anyways, what are your stories?
fstab bind mount for /home that I misspelled, so I couldn't login as myself.
fstab external hdd mount that didn't have ignore flag so PC would pop if I booted while unplugged
Accidentally booting windows after a year and it overwrite my EFI boot entry.
The best I've see however was an acquaintance who accidentally set perms to own user on /usr/bin
So everything went from root:root to user:user which removed all the SUID/SGID bits as well so a bunch of bins broke lol.
Believe it or not, it was actually fairly easy to fix with chmod and chown
I have an embedded device that runs as root and has busy box. I accidentally ran chmod -x on one of the busy box sym links (strings I think) and it made all of the core utils un-executable. Unfortunately chmod is a core util. Every bash command was throwing wild errors and outputing gobbledygook. You really start to sweat when ls and cat stop working.
I had full disk image of the device and started deducing the issue. Luckily I could still execute non core utils and ssh/scp was working so I wrote a little program to restore permissions, uploaded/ran the binary, and learned nothing from the experience.
Had the issue with the ignore flag missing literally a week ago. I mounted the HDD to troubleshoot it, ended up kicking the bucket, couldn't read any partitions from it anymore, but I had the Partuuid in fstab. Had to plug the main drive of the system into another one to fix fstab....