If you need to revert to a previous version of macOS or you are troubleshooting and decide to reinstall your Apple Mac’s operating system. While you can usually reinstall macOS through recovery mode. If you suspect that your computer was compromised or recovery mode won’t load. You will need to use some sort of recovery media in order to reinstall macOS.
So in this video we walk through the process for downloading a clean instance of macOS, and then use terminal commands in order to build a self-booting USB flash drive which contains the recovery media for macOS.
Note: In order to build your recovery media, Apple recommend that you use a blank 32Gb flash drive. While this might be a little over kill, and a 16Gb drive might do. We recommend that you use a 3.1 USB flash drive.
- Open a terminal window.
- Download a copy of macOS that you want to use as your recovery media using the command:
Softwareupdate --fetch-full-installer --full-installer-version (and then the version number of macOS we want to download)- Confirm the download has completed by checking that its in Apps.
- Connect your blank USB flash drive to your computer.
- Rename the flash drive MYVOLUME.
- Open the Apple article Create a bootable installer for macOS.
- Copy the appropriate terminal command for the version of macOS you are creating a bootable installer for. We will be using the command for macOS Tahoe.
- In the terminal switch to an account that has administrators rights.
SU [account name with admin rights]- Now paste the terminal command you just copied, for example:
sudo /Applications/Install\ macOS\ Tahoe.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume- Wait until you receive the message, “install media now available at …“
- Remove the USB flash drive until you need it.
- Close the terminal window.
- Power down your Apple Macintosh computer.
- With our computer switched off, plug in your recovery media.
- Press and hold down the power button until you see the message “loading startup options“
- Release your finger from the power button and wait for the computers boot menu to load.
- You will see three icons with the macOS recovery media icon in the middle.
- Use the mouse pointer to click on the recovery media icon to show a continue button.
- The installer will load allowing you to reinstall macOS on your computer.
- Mydoodads article – How to run a diagnostic test on an Apple Macintosh computer (Silicon hardware).
- Mydoodads article – How to factory reset macOS.
- Mydoodads article – Use Time Machine to restore an Apple Silicon Mac back to a previous state.
- Mydoodads article – Boot from a USB flash drive on an Apple Silicon computer.
- Apple support article – Create a bootable installer for macOS.
