If you want to put your Mac into recovery mode, boot from a USB stick, or start testing your hardware using Apple’s diagnostic tools, you’ll need to use the right combination of startup keys.
These keyboard shortcuts let you speed up your Mac’s normal boot process and can even change the behavior of macOS when you log in. Here’s a handy guide to different Mac mode boot options and startup buttons, when you might need to use them.
macOS Boot Mode and Key Combinations
To use these Mac startup commands and launch certain boot modes, you must first press the power button and then immediately press and hold the desired key combination.
On older Macs, you can wait until you hear a boot sound before holding up a shortcut. However, new Macs no longer make a sound at startup, so you should be holding the lock right away.
Startup Manager / Boot From USB: Option
Apple’s startup manager prevents your Mac from booting the default startup volume. Instead, you’ll get a list of all connected volumes, including USB and external drives. It’s very useful if you need booting Mac from USB or install Windows from a USB stick.
On some non-US Mac keyboards, the key Options not labeled as such. In this case, it is the button Alt what you’re looking for.
Safe Mode: Shift
If your Mac needs troubleshooting for startup issues, Safe Mode (also known as secure boot) is a good step to try. This forces your computer to load only the basics needed to start the operating system. Your startup disk will check for errors and perform repairs, and only use the necessary kernel extensions.
This mode also prevents opening and entry items from opening when your Mac starts up. This disables user-installed fonts and also clears some of the macOS system cache.
Apple Hardware Test / Apple Diagnostics Category: