I once sent around 40 computer science students
home early with a three character unix script
file. I was just trying to learn
about how the system worked and was messing about with scripts that spawned
other scripts when I thought of this one. The file was called simply a
and it's contents were...
When it ran it ate up all the available processes on the server. This meant that I had no obvious way of stopping it running because there were no free processes that I could use to kill it. Unfortunately the whole class were working on the now overwhelmed machine and found they couldn't do anything with it.
Eventually, I got it by logging onto another server with access to the same hard disk and deleting the script file.