Mac OS - Startup Keyboard Commands
This document lists helpful keyboard commands that can be used at startup.
Startup Keystrokes
| Keys | Result |
| C | Forces the Macintosh to boot from a CD, DVD, or USB thumb drive if it is present |
| T | Starts the computer in Target Disk Mode. One can then access the internal hard drive by connecting the computer to another via firewire, thunderbolt, etc. |
| Shift + up arrow | Start up in Safe Mode. |
| Spacebar | Opens the Extension Manager (Mac OS 9 only) |
| Command | Turns off virtual memory (Mac OS 9 only) |
| Command + R | Boots from the recovery partition, if present (Mac OS 10.7 and up) |
| Command + S | Starts the computer in Single User Mode, where the user can interact with a command terminal. |
| Command + Option | Rebuilds the desktop (Mac OS 9 only) |
| Command + Option + P + R | Clears PRAM |
| Option + Command + Shift + Delete | Bypasses the current startup volume the Macintosh will try to boot from the next available device that has a valid system folder |
| Hold down Mouse button | Ejects removable media |
| Option | Allows you to select a boot volume on open firmware machines |