While assisting one of my staff with a problematic installation of some open source software on a server, I decided to clean up certain files that we no longer needed with “rm -r *”.

Only to discover that I was in the wrong directory.

It didn’t help that we had been working directly on that computer for several days.

I was saved from losing a week’s work only by the fact that the backup from the morning was good (you never know with backups). We still lost a few hours of work, but that’s much better than it could have been.

Moral of the story: a) backup even more regularly than you think necessary, b) keep a local copy of your working files, c) don’t use “rm -r *” unless you’ve double checked what it will do.