Press and hold the keys immediately after you press the power button to turn on your Mac. Keep holding until the described behavior occurs.
|Hold during startup||Description|
|Shift (⇧)||Start up in Safe Mode.|
|Option (⌥)||Start up to Startup Manager.|
|C||Start up from a bootable CD, DVD, or USB thumb drive (such as macOS install media).|
|D||Start up to either Apple Hardware Test or Apple Diagnostics, depending on which Mac you're using.|
|Option-D||Start up to either Apple Hardware Test or Apple Diagnostics over the Internet.|
|N||Start up from a compatible NetBoot server.|
|Option-N||Start up from a NetBoot server using the default boot image.|
|Command (⌘)-R||Start up from macOS Recovery.|
|Option-Command-R||Start up from macOS Recovery over the Internet.|
|Command-S||Start up in single-user mode.|
|T||Start up in target disk mode.|
|X||Start up from a macOS startup disk when the Mac would otherwise start up from a non-macOS startup disk.|
|Command-V||Start up in verbose mode.|
|Eject (⏏), F12, mouse button, or trackpad button||Eject removable media, such as an optical disc.|
- These combinations work with Intel-based Mac computers.
- If your Mac is using a firmware password, some of these combinations require you to enter the firmware password before startup completes.
- Other Mac keyboard shortcuts are available after your Mac has started up.
- Reset the System Management Controller (SMC) on your Mac