Boot Keys for Mac OS X System Start
Every Mac has a variety of optional boot functions that can be used to intervene during the Mac OS X system startup. These are typically in the form of a single keys held down, or a press of keystrokes and hotkeys, used to issue a command and thereby adjust the booting behavior of Mac OS X. The effects of holding the different keys on boot are varied, and each can be desirable for a wide variety of applications.
The booting keys available to Macs upon Mac OS X system start are listed below.
To use these and to gain the desired effect on the system, start holding down the appropriate key or keystroke immediately after hearing the boot chime on a Mac, or as soon as you see the Apple logo – that can either be booting from a cold machine, or during a system restart, just be sure to hold down the appropriate key early enough in the loading process to gain the effect, otherwise you’ll need to reboot and try again.
Mac Boot Modifications Keystrokes & Effects on Mac OS X System Start
These will be listed as the boot keystroke followed by the effect on Mac OS X:
- Option – Boot directly to the Startup Disk manager, where you can select to boot from any attached drive
- Command+R – Boot into Recovery Mode of Mac OS X (modern versions of Mac OS X only)
- C – Boot from a CD/DVD
- T – Boot in Target Disk mode (FireWire or ThunderBolt only)
- N – Boot from an attached network server (NetBoot mode)
- X – Attempt to force Mac OS X to boot
- Shift – Boot up in ‘Safe Mode’ which has limited functionality but disables third party extensions
- Command+V – Boot into Verbose mode
- Command+S – Boot in Single user mode
I find myself using all of these tricks relatively frequently in Mac centric IT work, but even for home users they may be necessary from time to time in order to perform a variety of tasks, whether troubleshooting, repairing, or just learning about a Mac.
If you have individual use cases or tips regarding startup boot keys that modify the Mac boot sequence or activity, share them in the comments below.