AppleJack is a script that bundles together all the common maintenance tasks that you might have to do to fix a misbehaving Mac. It is just a shell script (albeit a long and complicated script), so it does nothing you couldn't do yourself, but it conveniently bundles it all into a menu driven interface.
If you are curious about how it works, you'll find the script at '/var/root/Library/Scripts/applejack.sh' - and an "applejack" alias in root's .profile points to that. YOU SHOULD ONLY RUN APPLEJACK IN SINGLE USER MODE. Actually, parts of it could run in any mode, but if you aren't geeky enough to understand what can be done when, just don't mess with it. Use it as it was intended to be used. If you "sudo /var/root/Library/Scripts/applejack.sh", you'll be warned that you are in dangerous territory.
Normally, you get to single user mode by holding Apple-S after the "bong" of startup. I had forgotten that I had disabled that ability by setting an Open Firmware Password. It took three reboots to convince me that something was wrong and to remember that, and then when I went to run the version that I had installed pre-Tiger, that didn't work, so I had to go get the new 1.4 app from my OS install disk. Of course that had been packed away, and I couldn't find it, which caused my wife to ask why I was muttering and growling so much.
I did find the Tiger DVD, and dragged the app to my disk, and ran it to remove the firmware password. If I hadn't found the DVD, I still could have fixed this by holding Alt-Apple-O-F at startup. I'd have to know the password (I did), but as long as I had that, I could have typed "reset-nvram" and "reset-all" to clear it. Beyond that, I'd need to take things apart physically, but the Open Firmware Password.app worked, and I was then able to boot single user with Apple-S.
I also had forgotten that my Return key had broken and fallen off a long time ago. I've been using "Enter" ever since, which is fine in ordinary use, but not in single user mode. I could fix that with a "stty", but Ctrl-J also works, so I typed "applejack^J".
I suggest you read the manual fully before doing this. I didn't, but you really should.
AppleJack can take quite a while to run. You probably want to do "applejack auto" and go have coffee. When you reboot after doing all these repairs, your Mac can take an unusually long time to start up, so again you need to be patient (I don't do "patient" very well; I hope you are better at it).
You can review the log of everything AppleJack did at /private/var/log/AppleJack.log. I had a few minor permissions issue and a supposedly corrupt plist for a program I don't use any more.
AppleJack is something you should have on your Mac.
Got something to add? Send me email.
More Articles by Tony Lawrence © 2009-11-07 Tony Lawrence