AppleJack: The Best Mac OS X Troubleshooting Tool
AppleJack is free and open source. It runs a suite of unix tools on your boot volume to repair it (fsck), clean system/user caches, repair permissions, validate preferences files, and delete swap files. These are all common maintenance tasks that many/most of the Mac OS X maintenance programs do.

Unlike most of the other system maintenance utilities out there, AppleJack runs at the command line, specifically the CLI you get when you boot into Single-User Mode. This means that if your computer cannot boot to the GUI, but can still boot to Single-User Mode, you'll be able to run AppleJack's utilities. We have AppleJack installed on our lab and classroom computers and I've encountered quite a few machines like this, and in most cases, AppleJack has been able to fix the problem. It's faster to do this process than boot the computer from Firewire Target Disk Mode, or from a System CD, and run Disk Utility (essentially, fsck) to repair the boot volume.
AppleJack is currently at version 1.4.1 and works with Mac OS X 10.2 and above, including Tiger.
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There are a lot of Mac OS X maintenance programs out there: Onyx, Cocktail, MacJanitor, SystemOptimizer, etc., but I want to put the...
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AppleJack is great, with one caveat: If you have to repair a TON of permissions (people who have installed Quark 6 know what I mean), it is quite a bit slower than running DiskUtil... as in orders of magnatude slower. Outside of that, it's a GREAT utility!
December 06 2005 at 12:28 PM Report abuse Permalink rate up rate down ReplyMac OS X's fan management software isn't loaded in single-user mode, so on some Macs -- especially Power Mac G5 models -- your fans will start to ramp up to full, jet-engine levels.
December 06 2005 at 2:26 AM Report abuse Permalink rate up rate down ReplyI just ran AppleJack on my new iMac G5. A Help Viewer problem that's been vexing me is now gone. Glory be. The fan ran at full speed the entire time I was in Single User Mode, much faster than I've heard it before. I'd want to figure out how to turn it down next time. Is there a CLI tip for that?
December 06 2005 at 1:16 AM Report abuse Permalink rate up rate down ReplyThanks for the heads-up. I've managed to completely miss this one up to now.
December 05 2005 at 8:49 PM Report abuse Permalink rate up rate down ReplyI've used AppleJack for a long time and have installed it on every Mac that anyone trusts me with. It's not just for problems either...it's helpful for general maintenance. -luke
December 05 2005 at 5:20 PM Report abuse Permalink rate up rate down ReplyLove AppleJack...I've been using it for about 8 months now and it's solid.
December 05 2005 at 4:59 PM Report abuse Permalink rate up rate down ReplyOooh, this looks nice. Thanks for the tip.
December 05 2005 at 4:03 PM Report abuse Permalink rate up rate down ReplyHot Apps on TUAW
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