Apple Mac boot options

mac_boot_options.txt

Mac boot options
Hold keys at startup.

Startup Manager: Option (⌥)
Set boot source as default: Get to Startup manager then hold Control while selecting the disk
Boot from CD/DVD/USB: C
Target Disk Mode: T
Check for Option ROM firmware: Option-Shift-Command-Period

Safe Mode: Shift (⇧)

Apple Hardware Test: D
Apple Hardware Test over the Internet: Option (⌥)—D

Install the latest macOS that was installed on your Mac: Command (⌘)-R
Upgrade to the latest macOS compatible with your Mac: Option-⌘-R
Install the macOS that came with your Mac, or the closest version still available: Shift-Option-⌘-R

Single-User mode: ⌘-S
Verbose: ⌘-V
Boot from NetBoot server: N
Boot from NetBoot server using the default image: Option (⌥)—N

Reset PRAM/NVRAM: Command (⌘)—Option (⌥)—P—R, then release the keys after you hear the startup sound for a second time
Reset SMC: Shut down your Mac, and then press and hold the left-side Shift (⇧)—Control (⌃)—Option keys along with the Power (⎋) button, all at the same time, until the computer turns on. Now release the keys and then turn your Mac back on using the power button.

Eject removable media: Media Eject (⏏), F12, mouse button or trackpad button

OS X Startup Volume: X (will start up your Mac from an OS X startup volume when it’d otherwise boot from a non-OS X volume, like a Windows partition)

Prevent Login Items from opening: To override your current settings and prevent Login Items and Finder windows from your last session from opening when you log in, hold down the Shift (⇧) key after clicking the Log In button in OS X’s login window until the desktop appears.
Prevent automatic login: If you enabled the option to automatically log a specific OS X account every time your Mac starts up, you can override this setting by holding the left Shift (⇧) key after OS X’s boot progress indicator appears.