HOW TO RUN FSCK (DISK REPAIR UTILITY) IN SINGLE-USER MODE:

The way Jaguar's file system works, you can't actually run any sort of disk utility on a disk partition while booted up to that partition (sort of like the way you couldn't repair most of the important stuff in pre-OSX while booted to the disk you were trying to repair). If you open up Disk Utility, your drives and partitions will list over to the left of the window. If you select your boot partition and then click on the First Aid tab, you'll see that the Verify and Repair Disk tabs are grayed. Although you can Verify and Repair Disk for any partitions or volumes that are not the current boot partition, ya can't repair a partition you are running from. That's pretty difficult if you only have one boot partition with both OSX and OS9 installed there. And booting from a CD is SO painfully slow with OSX...

Check out Apple's Knowledge Base for an alternative explantion.

So, Apple allows you to enter what is called Single User Mode. Reboot your machine and as soon as you hear the 'bong', hold down the Command (Apple Key) and 'S' keys. Continue holding them down until you see some rather obnoxious looking old ASCII text go streaming down the screen. This means you are booted up outside the Jaguar User GUI and can directly perform file system repairs. Once you get to a cursor prompt (a solid white box that doesn't blink), type in the following without quotes,

fsck -y

(note the blank space before the "-y"). All this means in code is "File System Check, yes to all" It will immediately start running through your boot partition and looking for and correcting any problems. This can take a while; the Mac OSX file system has tens and tens of thousands of files.

When it is finished checking the disk, it will give you a one-line report. If it found problems, it will state "Disk X has been modified." If no problems were found, it will state "Disk X appears to be OK." If you get the "...modified" statement, run "fsck -y" again repeatedly until you get the "...OK" statement. This check may need to be run up to four times on a system with serious problems.

When you get the "...OK" message, type

Reboot

This will restart your machine and return you to the User GUI interface you know and love. Perform this once a week, or whenever you smell trouble. It can't hurt you and it might help catch a problem before the problem catches you!