To access some specialized Mac features, you’ll need to hold down one or more keys during startup. These specialized boot option shortcut keys are crucial for troubleshooting and diagnosing your Mac.
To use any of these boot keys, hold down the listed key or key combination as soon as your press your Mac’s power button. If you’re restarting your Mac, press and hold the keys immediately after your Mac begins to restart. Don’t release the keys until you see the described behavior. If you’re using these commands on a laptop, make sure you’re using the built-in keyboard.
Shift: Start up in Safe Mode. Safe mode only loads essential software, helping you determine whether a system process or a user-installed application is giving you difficulty.
Option: Start into Startup Manager. This will allow you to select different startup disks, if any are available.
Command + R: Boot into Recovery Mode. Recovery mode allows you to reinstall macOS, back up from Time Machine, or use Disk Utility to repair or format a hard drive. If you’ve damaged your macOS partition beyond repair, you might need to replace it using the “Reinstall macOS” option here.
Shift + Command + Option + R: Start in Internet Recovery Mode. If you cannot boot up in Recovery Mode, use this key command to boot over the Internet. This allows you to reinstall the build of macOS that came with your computer from the factory.
Command + S: Start in single user, command-line-only mode. This is useful for running diagnostic Terminal commands or
Command + V: Boot in verbose mode. This mode displays logging and diagnostic messages as your Mac boots. This is useful for pinpointing a problem that’s preventing your Mac from booting completely. If your Mac is showing the Apple logo but failing to start completely, try this step to see where the error is.
Command + Option + P + R: Reset your Mac’s NVRAM or PRAM. This small memory module stores certain settings essential your Mac’s operation. If you’re experiencing hardware issues, resetting the NVRAM or PRAM can clear things up. Hold down the key combo as your Mac boots, then release it after about 20 seconds. If you have a Mac that plays a startup chime, you can release the key combination after the second startup sound. During the reset process, it might seem like your Mac is restarting before starting up normally.
Shift + Control + Option + Power: Reset the SMC on a MacBook. The SMC, or System Management Controller, is responsible for low-level hardware functionality. This includes fan speed, battery charging and sleep routines, among other features. If you’re having trouble with the features, resetting the SMC can sometimes fix the issue. To do so, hold down the Shift, Control and Option keys on the left side of the built-in keyboard. Then, press the power button at the same time. Hold the keys and power button down for ten seconds. Then, release all the keys and start the computer normally. Resetting the SMC is not the same as resetting your PRAM or NVRAM. This command will not reset NVRAM or PRAM.
C: Start up from a CD, DVD or USB thumb drive that contains a valid Mac operating system. This is an abbreviated version of Startup Manager, which can be used in place of this command.
T: Start up in Target Disk mode. Use this command on the computer that should behave like a hard drive. Note that the target computer must be connected with a Firewire, Thunderbolt or USB-C cable.Eject; Mouse button; Trackpad button; F12: Eject removable media, i.e. eject CD or DVD from the optical disc drive.
X: Force the system to boot from your macOS startup disk. This is especially useful when a competing Windows installation has set itself as the default boot partition on your Mac.
Option + D: Start the appropriate diagonistic utility over the Internet, bypassing your computer’s internal storage system.
N: Start from a compatible NetBoot server, if there is one available.
Option + N: Boot from the default boot image on a compatible NetBoot server.