I've had very similar experience. I believe it was Oracle 7 and one smart guy tried to install it into the root folder. The only problem was that the install script did 'rm -rf $DESTFOLDER' at the beginning. Luckily for us, the script actually printed the commands on the console and the guy quickly realized what is about to happen. He aborted the install script but by the time /etc and quite a few other things were gone.

It was a Sun OS 5.1 I believe on a pretty big box (for its time) with A LOT of user data. We recovered it using roughly the same steps. We didn't need to write in assembler though since we've had Sun compiler tool chain in /opt that survived. At the end, we used a modem to connect the damaged box to another one with a tape backup. It took about 12 hours to copy the data over.

Thanks for that. I had this strong feeling that this was very much basically the same as something (classic) that I had read before.