What's the biggest programming mistake you've ever made?

Is there any way we can stop with the reddit and Rolling Stones posts?

Just as a heads-up, this reddit post is 2 years old.

About twelve years ago, I wrote a CGI script with a loop like "for(i=10;i>0;i++){}", with the counter going in the wrong direction. Since it was running as apache, I did not have rights to kill it. My buddy used this server for his business and I had DOSed it for about fifteen minutes until the integer overflowed. If the language had used a bignum, it would have been worse.

I made as similar mistake on the school's server a couple of years later when I had an infinite loop in an XSLT file that I was developing. Fortunately, libxslt had a way of detecting infinite loops in which it logged a warning to /var/log/messages and, far less fortunately, repeated the loop. Once again, I did not have rights to stop it and I had run it on a weekend when nobody was working. The hard drive was full well before anyone came in to work on Monday.

Lessons learned: Test web-based programs from the command line whenever possible. If you're a server admin, let your users' CGIs run under their identities and consider using resource limits.