AppleJack Is The Basic Mac Safety Utility You Need.

Troubleshooting a wonky Mac can be a challenge. I’m the administrator for over 100 Macs which run OS X Leopard and Tiger.

One of my most beloved utilities to help troubleshoot an errant Mac is AppleJack, now Leopard compatible. About time.

AppleJack is something of a geek’s utility, a troubleshooting utility for Macs that have gone astray, an assistant that is there only for the bad times.

There are many utilities which do some of what AppleJack does. They repair permissions, check and validate your Mac’s system’s preference files, and open up a bunch of hidden preferences.

These little utilities are all well and fine and useful and usually free. What most of them do not do, and what AppleJack does, is save your bacon by letting you start up your Mac even when it doesn’t want to start up.

What? A Mac so wonky that you need a nearly one-trick pony to get it to work? OS X is a complicated beast and sometimes it doesn’t just work.

The reasons are many and varied. System preferences can become corrupted. Ditto for various and sundry cache files. The hard drive might need repair.

Outside of tracking down hardware problems such as a ready to die or dead hard drive, or a fried motherboard, AppleJack gives you access to your Mac when your Mac doesn’t like you any more and won’t let you in the front door.

Think of AppleJack as the back door utility you need in an emergency. It ain’t pretty, but it’ll get you there.

Not pretty? Nope. Not anywhere close. If all you know is Mac or Windows and can’t spell DOS, then AppleJack is something of a throwback to the last century. It even looks like the ancient of days, DOS—the PCs command line interface our elders told us about.

Once you install AppleJack it just sits there waiting for you to have a problem. When your Mac behaves all strange as if it has forgotten who you are, the you can invoke AppleJack.

Invoke? Sounds geeky. Well, it is. Sorta kinda geeky, though relatively simple if you can read.

Sometimes your Mac just won’t let you in the door. For whatever the reason, and there’s usually a good one—corrupt files, goofy permissions, an OS X update that went bad—when a Mac goes bad you just want it to go back to being your friend.

If you happen to have your Mac’s startup DVD (sure, you carry that around with you all the time, right?), then you can use that to start up your Mac and check your files, permissions, even repair your Mac’s hard disk.

AppleJack lets you do all those things without the necessary startup disk. The interface isn’t pretty but it works.

Start up your Mac in what is known as Single User Mode. Yes, you’re probably your Mac’s only user, but single or not, there’s a special mode that AppleJack likes. Single User Mode, or SUM, can be invoked by starting your Mac and holding down the Command an ‘S’ keys at the same time.

At the prompt, circa 1976, enter the word applejack or applejack auto.

The latter runs through all the assigned tasks automatically and will restart your Mac when it’s done. The former gives you a menu with various settings to use manually.

The settings include Repair Disks, Repair Permissions, Cleanup Cache Files, Validate Preference Files, Remove Swap Files, and Quit. Type in the number of the selection and sit back and watch. And wait.

Oh, one more thing. Stick with the basics. AppleJack is designed to start up in Single User Mode. If you’re adventurous and not afraid of catching leprosy by using your Mac’s Terminal application, you may be tempted to start AppleJack from the command line. Don’t.

AppleJack is very easy to install, easy to use, but you may forget it’s there. Once installed, should your Mac begin behaving as if it is Windows XP with a cough, then restart, hold down the Command and ‘S’ keys (‘s’ for Single User Mode), then type applejack.

Click Here to download AppleJack. Sleep better tonight.