Boot Commands

From Applepedia

Boot Commands

Press and hold the key or combination of keys right after you power the machine on or during a reboot. Hold it until you see the grayscale Apple logo and spinning indicator. Note: the "Command" key is sometimes referred to as "the Apple key" or "Fruit."

⌘-S Boot into Single User mode, handy for fsck'ing, trouble shooting, and I would figure resetting passwords but I'm afraid of NetInfo so I have not bothered.

⌘-V Verbose boot mode. Just like you see on most other UNIX boot ups it will show fsck'ing, mounting, kernel stuff, etc. Handy if it does not completely boot up so you can see where it's hanging. To make this permanent, run sudo nvram boot-args='-v' in Terminal.

T Boot into Firewire target disk mode.

⌥ Boot into Open Firmware to select a boot device, a nice GUI should appear and list bootable devices.

C Boot off of internal optical drive. I don't know if it will boot off of a Firewire enclosed drive as I haven't tried it.

Mouse button Or left mouse button if you're not Steve Jobs, ejects internal optical drive.

N Network boot, never had the chance to fiddle with this. I wonder if it's similar to Sun's network booting?

X Reset startup disk selection and boot into Mac OS X Server.

Shift Boot into "Safe Boot" mode, which runs Disk First Aid. A reboot will be required afterward.

⌘-⌥-Shift-Delete Bypass internal harddrive on boot.

⌘-⌥-P-R Reset Parameter RAM (PRAM) and non-volatile RAM (NVRAM). Hold it until the computer chimes three times.

⌘-⌥-O-F Boots to the Open Firmware prompt.

⌘-⌥ after the Apple logo. OS 9 and below will rebuild the desktop, not needed in OS X.

Clear Open Firmware values

To clear all Open Firmware values that may be causing issues, such as poor battery performance on portables perform the following steps.

1. Turn the computer completely off.
2. Hold down Shift-Ctrl-⌥ and press and release the power button.
3. Wait 5 seconds.
4. Turn the computer back on.
5. As the computer is powering on, hold ⌘-⌥-P-R until you hear the chime three times. It will take awhile between each chime.
6. After the third chime, switch to ⌘-⌥-O-F to get into Open Firmware.
7. Run set-defaults.
8. Run reset-nvram.
9. Run reset-all. The computer will reboot at this point.