Big Sur Disk Install Override | Text

December 14th, 2021 12:06:52 PM

Newer Mac computers have a security setting that prevents them from being booted from a USB drive which makes the process of performing a Clean Install from a USB drive (wipe computer and install OS from bootable USB drive) more complicated. While still possible, it involves a few extra steps. This documentation is written specifically for Big Sur. For other versions of MacOS, references to Big Sur will need to be changed. Before you start, you must have the OS installer on a USB drive. The best way to do this is to build install media with the built-in utilities. The instructions for which can be found here: Boot the computer into recovery mode. Using Disk Utility, wipe the drive from the root level. This must be done by “viewing all devices” and erasing the physical root drive rather than just the primary partition. When you wipe the drive, note the name that is used. This is crucial as you will need the name in step 4. For this documentation, we will be using the name “Untitled.” From Terminal, verify the name of the bootable installer by entering the following commands: cd /volumes ls -l Typically, this will result in three drives: the USB Installer, “Untitled”, and a startup partition (the recovery partition)2 Note the name of the USB Installer, you will need this for the next step. For this documentation, we will be using the name “Install macOS Big Sur” From Terminal, enter the following command to start the installer (example names will be highlighted in yellow) /Volumes/Install\ macOS\ Big\ Sur/Install\ macOS\ Big\ --agreetolicense --nointeraction --volume /Volumes/Untitled/ As with all BASH scripting, escape characters ( \ ) are necessary anywhere there are spaces in the command line (as in the example above) The trailing “/” is necessary. Do not omit it. How to create a bootable installer for macOS You can use an external drive or secondary volume as a startup disk from which to install the Mac operating system.

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