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Mac Startup Keyboard Commands

People often ask about all the weird incantations of keyboard commands used at startup for Macs to perform various actions. Here's a list of some useful ones.

Please note that this table uses the convention of capital letters for command or control sequences. However, one doesn't actually press shift unless specifically directed. (E.g., "control-C" means control and lower-case "c")

Also please note that ⌘ = Command key, ⌥ = Option key, ⇧ = Shift, and ⌃ = Control.

Hold down... Performs this action When can I let go? Comments
General
⇧-⌃-⌥-power key System Management Controller (SMC) Reset Hold down before you power the computer on. Please see Apple's How to reset the SMC of your Mac page, because the details change, depending on your Mac model. (For example, whether to hold down the Left or Right Shift key!)
⌘-⌥-P-R Parameter RAM (P-RAM) Reset After the initial chime, hold down this key combination and keep holding until you have heard three more chimes. A useful way to reset a number of settings for a Mac that is behaving strangely. Resets AppleTalk, Volume, Mouse Acceleration, and a few others. Often a simple 'miracle worker'.
Hold down mouse buttonEject removeable media Hold until desired media ejects. Convenient way to eject floppies, Zips, or CDs at boot time.
CBoot from compact disc (internal only) Hold until background or splash screen clearly shows that you have booted from CD, not internal disk. Allows one to boot from CD without having to select it first in Startup Disk control panel/System Preference.
⌘-⌃-power key Reboot from keyboard Hold until you hear reboot chime. When machine is frozen, this allows you to reboot from the keyboard, which is analogous to hitting the left-triangle button on the Mac box. No longer works on new USB "Apple Pro" keyboards which lack a power key.
New World Macs
Start with Boot Selector Hold until icons of bootable devices appear. This allows you to choose what device to boot from, whether it is your regular boot disk, the Recovery Mode of your internal disk, an external disk, etc.
⌘-⌥-O-F Boot into OpenFirmware Hold until small black letters on white background appear. There are`a variety of commands you can run here (well beyond the scope of this document). Common ones include "mac-boot" and "shut-down". Only works on New World machines.
TThunderbolt, Firewire, or USB Target Disk Mode Hold until large white icon(s) appears on Mac screen, moving randomly. To allow a Mac to function as an external disk drive, do the following:
Boot Mac A normally. Boot Mac B into Target Disk Mode. Connect the two Macs together with an appropriate cable. The Mac B disk will appear on the desktop of Mac A. (If it is encrypted, you may first get prompted for a password for Mac B.)
OS X only
⌘-R Hold until progress bar appears Recovery Mode Ability to run Disk Utility, Terminal and more booted from a small read-only partition. Can also reinstall the operating system. Using Terminal is often more convenient than Single-User mode (and a lot more visible on Retina screens).
⌘-V Boot OS X with (V)erbose settings. Hold until until white on black letters appear. "Console" booting will give far more information about boot sequence. (More like Linux than the graphical OS X normal boot display.)
⌘-S Boot OS X in single-user mode Hold until until white on black letters appear. Useful for certain diagnostics and repairs of operating system.
Safe mode Not sure! Hold until FileVault screen appears, then release to type your password. Then immediately hold again until the PIV boot screen appears. (Release Shift to type PIN.) Then immediately hold again all the way until the Finder appears. If this succeeds, you should see "Safe Boot" in red letter on the menu bar. This can get past errors of faulty applications that would otherwise start (and won't here).
26 February 2002 (original)
14 April 2020