This content is 18 years old. I don't routinely update old blog posts as they are only intended to represent a view at a particular point in time. Please be warned that the information here may be out of date.
After my backup hard disk failed a couple of weeks ago, I needed to be sure that a hard reset of my Mac hadn’t damaged anything so I fired the machine up in single user mode and ran AppleJack.
As it happened, there was nothing wrong, but there’s no harm in a bit of preventative maintenance from time to time; however I had forgotten the keypress to bring Mac OS X up in single user mode – for future reference, Apple has a document which details OS X keyboard shortcuts.