Discussion on the Mac user group forum re the difference in terminology between using the Terminal App & single user mode made me remember an old utility app that was run from single user mode. That is Applejack & I know I'll have to install it on the G5 PowerMac & the G3 Pismo PowerBook. It is already on the G4 MDD PowerMac & might need to also be added to the G4 eMac. I'm not sure about the Titanium PowerBook, I need to do a bit more checking.
It's a really handy utility, repairs startup drives, repairs permissions, removes corrupt preferences, cleans out system & individual user caches and removes swapfiles.
It can be run manually or automatically, if AUTO is entered instead of auto, it goes into deep clean mode.
A way to determine if it's installed is to open Terminal app and enter 'man applejack'. If it's installed Terminal will open a user manual for the app.