How to Use Startup Keys to Resolve Mac OS X Boot Problems
Mac OS X includes a number of special keys that you can use during the boot process. These keys really come in handy when you need to force your operating system to do something that it normally wouldn’t, such as boot from a CD instead of the hard drive.
- To boot from a CD or DVD:Restart your Mac while pressing the C key. This is a great way to free your startup volume when you want to test it or optimize it using a commercial utility.
- To eject a recalcitrant disc that doesn’t show up on the Desktop:Restart Mac OS X and hold down the mouse button, or if you have a late-model Mac, press the Media Eject key as soon as you hear that magnificent startup chord.
- To force your Mac to boot in Mac OS X: Hold down the X key while restarting or booting the Mac.
- To display a system boot menu:Hold down the Option key while restarting or booting the Mac, and you can choose which operating system you want to use.
- To prevent start-up applications from running during login: Hold down the Shift key while you click the Login button on the Login screen. If you don’t see the Login screen during startup, just hold down Shift while Mac OS X boots until the Finder menu appears.
Mac OS X Startup Keyboard Shortcuts
Control The Startup Process in OS X
Starting up your Mac is usually just a matter of pressing the power button and waiting for the login screen or the desktop to appear. But once in a while, you might want something different to happen when you start your Mac.
These startup shortcuts come in handy if you need to troubleshoot your Mac, or you just want to boot from a different volume than usual.
Startup Shortcuts
- Hold the 'x' key during startup.This will force the Mac to boot from OS X, no matter which disk is specified as the startup disk.
- Hold the 'c' key during startup to boot from a bootable CD or DVD.
- Hold the 'n' key during startup to boot from a networked computer that has a NetBoot volume.
- Hold the 't' key during startup to boot in FireWire Target Disk Mode. This mode lets you use any Mac with a FireWire port as the source for your bootup system.
- Hold the 'd' key during startup. If the Apple Hardware Test DVD is in the optical drive, the Apple Hardware Test will begin.
- Hold the option key during startup. The OS X startup manager will appear, allowing you to select a disk to boot from.
- Hold the shift key during startup. This will boot your computer in Safe Mode. Safe Mode disables login items and non-essential kernel extensions from starting up.
- Hold the command + r keys during startup.This will cause your Mac to use the Recovery HD partition, which will allow you to restore OS X Lion or later.
- Hold Command + 'v' during startup The command key is the key with the cloverleaf symbol. This shortcut will boot your Mac inVerbose Mode, with descriptive text sent to the display during the startup process.
- Hold Command + 's' during startup. This shortcut will boot your Mac in Single-User Mode, a special mode used for troubleshooting and repairing complex hard drive issues.
- Hold down the mouse's primary key during startup. On a two- or three-button mouse, the primary key is usually the left button. This shortcut will eject a CD or DVD from the optical drive.
- Hold Command + Option + 'p' + 'r' during startup. This zaps the PRAM (Parameter RAM), an option that long-time Mac users will remember. Press and hold the key combination until you hear the second set of chimes. Zapping the PRAM returns it to its default configuration for display and video settings, time and date settings, speaker volume, and DVD region settings.
In all cases, you should use the keyboard shortcut combinations immediately after pressing the Mac's power switch, or, if you used the Restart command, after the Mac's power light goes out.
