Startup shortcuts during Bootup in Macintosh

To use a keyboard shortcut, or key combination, you press a modifier key with a character key. For example, pressing the Command key and the "c" key at the same time copies whatever is currently selected text, graphics, and so forth into the Clipboard. This is also known as the Command-C key combination.

Press the key or key combination until the expected function occurs/appears (for example, hold Option button during startup until Startup Manager appears, or Shift until "Safe Boot" appears).

Key combination                                   Its Function

Option                                                     Display all bootable volumes (Startup Manager).
Shift                                                         Perform a Safe Boot (start up in Safe Mode).
Left Shift                                                  Prevent automatic login.
C                                                             Start from bootable media (DVD, CD, USB, and so on).
T                                                              Start in FireWire target disk mode.
N                                                             Start from NetBoot server.
X                                                              Force Mac OS X startup.
D                                                             Use Apple Hardware Test.
Command-R                                           Use Recovery (OS X Lion or later).
Command-V                                           Start in Verbose Mode.
Command-S                                           Start in Single User Mode.
Command-Option-P-R                           Reset NVRAM / parameter RAM.
Hold on the Media Eject (⏏) key              Eject removable discs.

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