Esoteric Mac Key Combinations

from Matthew's Apples
by Matthew Frederick Davis Hemming
January 2003

Mac novices are often surprised to learn that there is a fistful of arcane keyboard combinations that can be used to manipulate your Mac while troubleshooting. Since I see many people searching for explanations of these terms through Google in my referrer logs, I thought I would write-up the most common key combinations. And so:

In The Finder

Command + Option + I/0
This combination forces a hard reboot of your computer.

Command + Option + Escape
This opens the software Force Quit dialogue, for killing programmes that have frozen.

Escape
In most dialogue boxes pressing Escape activates the "Cancel" button. Handy time-saver.

Screen Captures

Command + Shift + 3
Current desktop is saved as a PICT file at the root level of your boot drive in classic Mac OS. In Mac OS X a PDF is written to the current user's desktop directory. In both systems you should hear a shutter-click sound effect play.

Command + Shift + 4
Cursor changes to crosshairs. Click and drag to define a rectangular area for capture. Release the mouse to make the capture.

Command + Shift + 4 + CapsLock
Cursor changes to a bullseye. Position it over any window and click to capture that window.

During Booting

Command + Option
This causes the Finder to ask to rebuild its database of files, locations and icons on a volume by volume basis in the classic Mac OS. This can he helpful is your Mac is having trouble with icons turning generic, and forgetting which application they are associated with. In Mac OS X this key combination will do nothing.

Command + Option + P + R
Often called "zapping the p-RAM" this command clears any information in the battery-powered parameter RAM. You'll know that you have been successful in clearing the first chunk of parameter RAM when you hear your Mac gong a second time. In some rare instances of corrupt parameter RAM you may have to hold down this key combination for two or three bongs, in order to flush out the entire cache. Release the keys and the computer will resume booting as usual.

Command + Option + O + F
On New World machines this brings up the OpenFirmware prompt. On Old World machines this does nothing at all.

Command + Option + Shift + Delete
This will force the Mac to ignore its own internal drive while hunting for a viable boot block. If you have a bootable operating system on an external drive, the Mac will attempt to run it.

C
Holding down the C key gives the Mac a polite suggestion to attempt to boot from an optical media drive, like CD or DVD-ROM.

Shift
Holding down the Shift key causes the classic Mac OS to launch without any software extensions, drivers or special plug-ins. If you suspect that you have a problem with an extension and cannot startup your Mac, try this. Holding down Shift will do nothing at all on machines running Mac OS X.

Space Bar
This will cause the classic Mac OS boot process to pause, and load up the Extensions Manager. There you can handling software extensions invidiually or in packages, marking them to load or not load when booting resumes. Holding down the space bar will do nothing at all on machines running Mac OS X.

Option
Holding down the option key before the booting of Mac OS X begins will bring up a simple graphical interface that allows you choose between operating systems if you have multiple operating systems installed.

9/X
Hold down the 9 key to boot into OS 9, and hold down the X key to boot into OS X.

Command + S
Holding down Command-S forces OS X to boot into Single User Mode.

Command + V
Holding down Command-V forces OS X to use verbose mode while booting, filling your screen with geeky text messages rather than the Mac logo with a patience bar underneath.

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