I have been toying with the idea of posting a thread asking for your dumbest mistakes so that we may all learn from each other.
"A smart man learns from his own mistakes,
A wise man learns from others' mistakes"
I think I will start us off. I haven't had too many that were really bad, but here goes. I was playing around on a box as ROOT when I was looking in a certain directory to see what scripts where there.
I was catting them to look but I inadvertently executed one of them when I deleted the cat and left only the command and hit enter by mistake. I didn't notice my handywork right away though. About 15 minutes later, people called me saying they can't login. Anyway, 3 hours later I finally figured out that when I exe that script it changes the permissionsn on your home directory to 444. Well, for me that was /.
Once I fixed that everything was fine.
I had 4 hours of downtime charged to OE, operator error. BTW, this was on a production system at work! Doh!!!