On any Mac OS X box, you can enter “single-user mode” by holding down command-S at startup. This gives you a root prompt and a read-only hard drive, from which you can commence your life of quiet desperation, er, troubleshooting.
Normally, you would do this to repair the drive :# fsck -y This is exactly equivalent to booting off the install CD and repairing your disk using Disk Utility. In Mac OS X, Disk Utility is a graphical frontend on top of fsck. It works just as well in single-user mode because the drive is mounted read-only, so there’s no chance of files being modified while the repair is running.
If fsck tells you that the file system was modified, reboot immediately :# reboot Repeat until fsck reports no errors. It is now safe to exit single-user mode and continue booting normally :# exit If you can not get to the login prompt, or your login window appears but shows no users and no username/password boxes, your NetInfo directory is probably corrupted. Reboot into single-user mode and trash it :# cd /var/db/netinfo
# mv local.nidb local.nidb.corrupted
# reboot Upon rebooting, Mac OS X will notice the missing NetInfo directory and will create a new blank one. This will not actually let you log in, however, since the new NetInfo directory contains no users. (Technically it contains a root user, but with login disabled.) Assuming you get to a login prompt, reboot once again into single-user mode and add a root password. This is trickier in 10.2 than it was in 10.1, but I believe this technique works in both (I’ve tested it personally in 10.2) :# SystemStarter Watch the status messages. When you see “Starting NetInfo”, hit CTRL+C to get back to a prompt, then type:
# passwd root
Password: (enter new password)
Verify password: (re-enter new password)
# reboot
Here you are essentially hacking your way into your own computer by changing the root password. (And if root was previously disabled, this has the side-effect of enabling it.) Rebooting should get you to a login prompt where you can log in as root and get to work recreating your other users or recovering your data or whatnot. (It should be noted that the above method will also work on anyone else’s computer, but don’t do that. If this scares you, install Open Firmware Password Protection, which is essentially a BIOS password for Macs, and prevents booting into single-user mode without a password.) Another fun thing you can do is force your Mac to always boot into single-user mode, without holding down any keys at startup :# nvram boot-args="-s"
# reboot Your computer should always boot into single-user mode from now on. To put it back to normal :# nvram boot-args="" Again, you can do this on anyone else’s Mac too, but don’t do that. Also check out this article at Apple's web site: Apple built -in repair utilities for OS X
Even though Macs generally require much less maintenance than Window's machines, there are still a few easy things you can do to keep your Mac running in tip top shape.
Repair Permissions Repairing permissions is one of the easiest and fastest maintenance tasks you can do on your Mac. You can start it easily at the click of a button, and let it run in the background while you continue to use your computer like normal. Each file on your Macintosh has a set of permissions, which say who and what can read or write to that file. When you install new programs, or when a file is corrupted, these settings can be changed and messed up. Generally they won't do anything major like crash your computer, but they can cause it to slow down over time. Luckily fixing the problem is very easy. To repair your permissions you need to start Disk Utility, which is in the Utilities folder in your Applications folder. Home > Applications > Utilities > Disk Utility After you open the application, click on the First Aid tab, then select the partition where Mac OSX is installed, in my case it is the "Macintosh HD". You don't need to select the entire hard drive, just the partition with your OS on it. Next click on Repair Permissions to start the process. You don't need to verify the permissions first. After you start the utility you'll see a bunch of text scroll by on the screen detailing what the application is doing, which files it's repairing, which ones are messed up, etc. After it's finished you can safely close the Disk Utility application. Periodic Maintenance My wife has the strange habit of cleaning and vacuuming the house at 1 or 2 in the morning sometimes. I don't understand this behavior, but at least she's not alone. Your Macintosh also cleans itself up at odd hours, namely between 2am and 5am each night. Mostly it's just deleting log files and cache's that it no longer needs, or backing up important files. But if your Mac is asleep or turned off, it won't be able to perform these tasks and those log and cache files will start to add up and waste space on your hard drive. So, to get rid of them manually we just need to type a few commands into the terminal which is also in the utilities folder. Home > Applications > Utilities > Terminal Type the first line below and then press return. It will ask you for your password, which should be the password that you use to login with. You may see a bunch of lines of code scroll by, which is normal. After you are returned to the command prompt again as you see in the screenshot, type the other two lines, pressing return after each, and allow them to run. sudo periodic daily
sudo periodic weekly
sudo period monthly Prebinding Forcing your Mac to update the prebinding will make it search through all of your application files and properly link them together, which can increase the overall speed of your computer, and how fast applications launch, etc. Open the terminal if you don't still have it open, type the following line in the terminal and then press return.
sudo update_prebinding -root / -force You'll see a lot of text scroll by in the terminal, which is again completely normal. Immediately reboot after it finishes and you are returned to the command prompt. After you reboot you should notice a significant speed boost to your machine. Programs should start faster, you should be able to switch between them faster, etc. Perform these steps any time you notice your computer going slower, and repair permissions every time you install a new program, especially something like an OS update from Apple. Easy way out To take the easy way out, you could also run a maintenance app likeOnyx and MacJanitor to perform these tasks at the press of a button. |