Basic key combinations tested on OS X 10.6 to allow more Mac boot options. These are mostly used for diagnostics.

Hold these keys down until you see a different startup screen than normal:

Key Action
Option (a.k.a. Alt) Boot Menu (use this to boot CDs)
d Boot into hardware diagnostics (F2 also works)
Shift Boot into Safe Mode (similar to Windows safe mode – basic OS X functionality – no kernel extensions)
Command-S Boot into Single User mode
Command-Option-P-R Reset PRAM & NVRAM (RAM that stores hardware settings). Hold this combination down until you hear the second OS X startup chime. This is useful if you have a gray screen on boot.

Note: if any of these key combinations fail and you are using a wireless keyboard, use a wired keyboard. If you are using a Macbook, just use your built-in keyboard.

Key Guide

  • Command –
  • Option –
  • Shift –
  • Control –
  • Power –
  • Eject – ⏏

Additional Mac Startup Key Combinations

This mac startup key combo article from Apple support shows a couple more options in case you're interested. If your Mac is using a firmware password, all of these key combinations are disabled, except as noted in the article.

That's all for now with this Mac boot options article. Is there a startup option you can't live without? What about one that wasn't featured in this article?

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