This question is related to another question -- "Can't access any functions after chown command." -- but I think it may be worthy of an independent question. My question is: how do I know that my system is messed up and that I should probably re-install? I already know that I made a huge stupid mistake, as is discussed on related question :) Here's what I did:
I wanted to learn a little about mysql. I know very little about databases and as you can tell from what I did, I know very little about linux. I was following instructions on this mysql tutorial page, accidentally ran the command:
/usr/bin$ sudo chown -R root .
After doing this, I realized my recklessness and naivete (all criticisms duly received) by getting the following error trying to run sudo:
sudo: must be setuid root
Besides enjoying using linux, part of my reason for using it is to gain experience, and thus, this mistake was not a total disaster. All my data are in the cloud, so it will just be the several hours of reinstalling everything that will cost me. But before I reinstall, I want to know how I can tell that my system is messed up. I was able to fix the "sudo problem" with the following helpful article: http://www.psychocats.net/ubuntu/fixsudo
I booted in recovery mode (by pressing shift during boot), I chose "Drop to root shell prompt," and then I think I ran the following commands:
mount -o rw/remount / sudo chown root:root /usr/bin/sudo sudo chmod 4755 /usr/bin/sudo
(The last two commands based on this askbuntu answer.)
After doing so and rebooting, sudo now "works" again, and I don't notice obvious problems with my system. However, as I have learned, my initial mistake changed ownership on the entire usr/bin directory and subdirectories. From what I hear, the best way to fix this is to reinstall the system and packages. But my question is: what kind of diagnostics can I do to know that my system is messed up from the ownership changes? So far things seem to work fine, such as: chromium, python, gedit, and apt-get. If I had made a different bone-headed mistake, I may not know I have a problem, so I am curious about some kind of diagnostic things I could check and what my primary motivation for reinstalling ubuntu would be. I am currently using Ubuntu 12.04 LTS. Thank you!