Troubleshooting User Initialization

If the process is not able to initialize the user environment, the user will never be given control of the graphical interface. You may see the user’s desktop background picture, but no applications will load, including the Dock or the Finder. Or it may appear that the user session starts, but then the login screen will reappear. At this point you should first attempt a Safe Login, which is initiated by holding down the Shift key while you click the Log In button at the login screen. Safe Login is also part of the Safe Boot startup mode. In addition to the Safe Boot procedures covered previously in this chapter, the displays the login screen with the words “Safe Boot” in bright red text under the Mac OS X logo.

With Safe Login enabled, the process will not automatically open any user-defined login items, and the user’s ␣␣␣␣␣␣␣ process will not start any user-specific LaunchAgents. Obviously, if a Safe Login resolves your user session issue, you need to adjust this user’s Login Items list from the Accounts preferences or any items in the /Library/LaunchAgents or ~/Library/LaunchAgents folders.

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Troubleshoot Logout and Shutdown

An inability to log out or shut down is almost always the result of an application or process that refuses to quit. If you’re unable to log out, as long as you still maintain control of the graphical interface, you can attempt to forcibly quit stubborn processes using the techniques outlined, You may find the process has closed your user session, but the Mac refuses to shut down. This is indicated by a small spinning gear icon on top of your desktop background or the bright blue screen after all your applications have quit. You should let the system attempt to shut down naturally, but if it takes any longer than a few minutes, it means a system process is refusing to quit. You can force your Mac to shut down by holding down the power-on key until the Mac powers off, as indicated by a blank display.

Troubleshooting the Kernel

Issues at the kernel stage are indicated by an inability to reach the bright blue screen, as evidence of a failure to load all KEXTs, the core BSD UNIX system, and ultimately the system process. If this is the case, your Mac is stuck at the light gray screen with the dark gray spinning gear icon.

To troubleshoot the kernel:
>Start up the Mac while holding down the Shift key to initiate a Safe Boot. In addition to the Safe Boot procedures covered in the “Troubleshooting the Booter” section ear- lier, this will force the kernel to ignore all third-party KEXTs. If successful, the kernel will start the system ␣␣␣␣␣␣␣ process, which will continue to safe-boot. Completing the kernel startup stage via a Safe Boot indicates the issue may be a third-party KEXT, and you should start up in verbose mode to try to identify the problem KEXT.

>Start up the Mac while holding down Command-V to initiate verbose mode. The Mac will show you the startup process details as a continuous string of text. If the text stops, the startup process has probably also stopped, and you should examine the end of the text for troubleshooting clues. When you find a suspicious item, move it to a quarantine folder and then restart the Mac without Safe Boot, to see if the problem was resolved. This may be easier said than done, as accessing the Mac’s drive to locate and remove the item may not be possible if the Mac is crashing during startup. This is an example of where FireWire target disk mode really shines. As covered in Chapter 4, “File Systems,” you can easily modify the contents of a problematic Mac’s system vol- ume using target disk mode and a second Mac.

N O T E :If your troublesome Mac successfully starts up in Safe Boot mode and you’re trying to find the issue, do not use Safe Boot and verbose mode at the same time. If the startup process succeeds, verbose mode will eventually be replaced by the stan- dard startup interface and you will not have time to identify problematic items.

>If the kernel cannot completely load while safe-booting or you are unable to locate and repair the problematic items, you may need to reinstall Mac OS X on that volume.

Troubleshooting the Booter

Issues at the booter stage are indicated by a flashing dark gray prohibitory icon—evidence of a failure to load the kernel.
To troubleshoot the booter:

>If you’re starting up the Mac from a volume containing a system this Mac has never booted from, the prohibitory icon usually indicates that the version of Mac OS X on the volume is not compatible with your Mac’s hardware.

>Start up the Mac while holding down the Shift key to initiate a Safe Boot. The booter will first attempt to verify and repair the startup volume, indicated by a dark gray progress bar across the bottom of the main display. If repairs were necessary, the Mac will automatically restart before continuing. If this happens, continue to hold down the Shift key. The booter will verify the startup volume again, and if the vol- ume appears to be working properly, the booter will attempt to load the kernel and essential KEXTs again. The booter uses the most judicial, and slowest, process to load these items. If successful, the booter will pass off the system to the kernel, which will continue to safe-boot.

>If the booter cannot find or load a valid kernel, you may need to reinstall Mac OS X on that volume.

Firmware Password on Mac OS X

Security goes beyond settings passwords and encrypting data. Mac OS X supports additional methods to secure the system itself. Setting a firmware password helps prevent circumvention of the OS-level security through an unauthorized boot device. Antivirus protection helps insure that any viruses that might come from other operating systems on the network won't threaten your data.

Firmware Password
You can configure a firmware password to enable low-level hardware protection for your Mac. A firmware password helps prevent unauthorized users from booting your Mac from an external hard disk, optical disc, or USB key drive. In order to complete this process you’ll need the Snow Leopard Install DVD.

To set a firmware password:
To set a firmware password, follow these steps:

1 Log in with an administrator account and open the Firmware Password Utility (located on the Mac OS X installation disc in /Applications/Utilities/)or(in recovery under utilities menu).
2 Click the "Require password to change Open Firmware settings" checkbox.
3 Enter a password in the Password and Verify fields.
4 Click OK. A confirmation appears. Click the lock icon to prevent further changes.

You can test your settings by attempting to start up in single-user mode. Restart the Mac while holding down the Command and S keys. If the Mac displays the login window after starting up, changes made by the Firmware Password Utility were successful.

To reset a firmware password:
To reset a lost or forgotten Firmware Password, access to the inside of the Mac is required (just like resetting a PC BIOS password requires removing the on-board battery).
To reset a firmware password, follow these steps::
1 Shut down the Mac.
2 Change the memory configuration by adding or removing RAM.
3 Start up the Mac (This will clear the firmware password).
4 Shut the Mac down again.
5 Return the RAM to its original configuration.
6 Start up the Mac

Note: For information on recovering a lost firmware password on a MacBook Air (Late 2010), refer to http://support.apple.com/kb/TS3554