At my first real technology job I worked at an early web hosting company. Cutting edge stuff in 1996. We hosted full domains for $60/mo and tilde domains (e.g.; domain.tld/~myname) for $25 or $30 per month.

We hosted on BSDi, a proprietary BSD and every domain customer had their own sub-directory with user and group ownership.

As an aside, BSDi would happily let you run `rm -rf .` and would walk up to root and back down through every sub-directory deleting everything on its way.

One day, probably a month or two into working at what was my dream job, I accidentally ran `chown -r zelphyr .` in the parent directory where we had all our domain customers instead of my personal domain directory. (I can’t remember why I was doing that.)

Instant panic. I just knew I was going to be fired. I sheepishly went to my boss, Todd, and told him what happened. He grinned and exclaimed, “Cool! A challenge!” and had me sit next to him while we wrote a Perl script to look at the paths in /etc/passwd and chown that directory back to its original user.

I’m eternally grateful to Todd for being such a great boss.

Edit to add: in reality, my biggest mistake early on was not learning fundamentals. How binary and processors work, how machine language works and how higher level languages compile down to machine language. I would be a much better programmer had I done so sooner.