Mac OS X: Starting up in Safe Mode

Summary

Learn how to start up in Safe Mode.

Products Affected

Mac OS X 10.4, Mac OS X 10.3, Mac OS X 10.2, Mac OS X 10.5, Mac OS X 10.6

To start up into Safe Mode (to Safe Boot), do this:

1. Be sure the computer is shut down.
2. Press the power button.
3. Immediately after you hear the startup tone, hold the Shift key. The Shift key should be held as soon as possible after the startup tone but not before.
4. Release the Shift key when you see the gray Apple icon and the progress indicator (looks like a spinning gear).

During startup in Mac OS X v10.4 or later, you will see "Safe Boot" on the login window, which appears even if you normally log in automatically.
During startup in Mac OS X v10.2 through v10.3.9, you will see "Safe Boot" on the Mac OS X startup screen.
To leave Safe Mode in any version of Mac OS X, restart the computer normally, without holding any keys during startup.

Additional Information

Advanced: If you can't Safe Boot with a keyboard
If for some reason you can't use the keyboard method to start in Safe Mode (the keyboard is missing or not working, for example), and you already have remote access to the computer, you can configure the computer to startup in Safe Mode via its command line

1. Access the command line by either opening Terminal remotely, or by logging into the computer from another via SSH.
2. Execute the following command in Terminal or on the command line:
   
   sudo nvram boot-args="-x"
   
   (If you want to start in Verbose mode as well, use sudo nvram boot-args="-x -v" instead )
    

3. After using Safe Boot, to return to a normal startup, execute this command in Terminal or the command line:
   
   sudo nvram boot-args=""

Ref >> http://support.apple.com/kb/HT1455?viewlocale=en_US