RecoveryOS

recoveryOS is the recovery environment used in macOS, watchOS, tvOS and audioOS.
This is not the same as the iBoot Recovery Mode available on most Apple devices, as this type of recovery environment requires the device to be plugged into a computer.

macOS

recoveryOS for macOS had its first introduction with Mac OS X Lion. At that time, Apple stopped selling Mac OS X through DVD's, and instead, they provided either USB sticks, or it could be downloaded through the Mac App Store. Apple also introduced a recovery environment, that in case a macOS installation is corrupted, it could recover itself by reinstalling macOS through the internet, without the need to reinstall macOS through a DVD.

Booting to recovery mode

Intel based Macs (including T2 Macs)

To boot to the local recovery mode, press Command + R at the same time during bootup until you see the Apple logo. To get the latest version of macOS (Internet Recovery), press Option (Alt) + Command + R at the same time until you see a spinning globe with text "Starting Internet Recovery. This may take a while.". You may need to choose a Wi-Fi network in order to download recoveryOS. To boot to the original macOS that your computer shipped with (or the closest version available), press Shift + Option (Alt) + Command + R at the same time until you see a spinning globe with text "Starting Internet Recovery. This may take a while.". You may need to choose a Wi-Fi network in order to download recoveryOS.

Apple Silicon based Macs

Press and hold the power button. You will see text "Countinue holding for startup options...". When you see the text "Loading startup options..." you may release the power button. Then choose Options (with the picture of a cogwheel (Software Update icon).

Whats included in recovery mode

- Restore from Time Machine: restore from a Time Machine backup.
- Reinstall macOS: installs macOS through the internet.
- Safari (minimal version, does not have the capability to play videos): User can use the internet to troubleshoot the Mac. The default home page is an HTML file which contains information about using recoveryOS.
- Disk Utility: Can be used to repair the disk using First Aid or erase the disk.
There are more utilities that can be accesed through the menu bar by clicking Utilities:
- Startup Security Utility: On normal Intel Macs, it can be used to enable/disable the firmware password (only on regural Intel and T2 Macs). On T2/Apple Silicon Macs, you can change the security settings and the allowed boot media settings.
- Share Disk (Apple Silicon Macs only): Can be used to transfer files from one computer to another. The equilant of Target Disk mode on Intel Macs.
- Terminal: Can be used for advanced troubleshooting, and it has the possiblity to enable/disable System Integrity Protection using csrutil.
File -> Choose Language: Switch between languages. This does not include the hello screen, which is normaly seen in the regular Language Chooser app.
Window -> Recovery Log (Command + L): view recovery log.
Country flag: switch between inputs.
Wi-Fi: switch between Wi-Fi networks
Apple logo -> Startup Disk: choose startup disk/boot to Target Disk Mode (only on Intel).

watchOS

Booting to recovery mode

Double press the side button when in iBoot recovery mode.

Usage

Can update/restore an Apple Watch using an iPhone (not just the paired iPhone).

audioOS and tvOS

Currently unknown.