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Jude
Jude

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Creating an External, Bootable, MacOS Installer

For every major MacOS release, I've gotten in to the habit of formatting my computer and doing a fresh OS install. I've done this a few way over the years, but my current process starts with creating a bootable external drive I can boot from.

My current process to create a bootable MacOS drive, is as follows.

Step 1. Find an external USB drive with at least 16GB of free space, and plug it in. This drive will be wiped, so make sure there is no data on it that you need.

Step 2. Open the terminal and enter the following command

softwareupdate --list-full-installers
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This will give you a list of available installers.
Terminal

Step 3. In the terminal enter the following command using the version number of the OS version you want to download.

softwareupdate --fetch-full-installers --full-installer-version 13.0
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This will take a while to download...

Step 4. Once the download has finished, back in the terminal write the following command.

sudo /Applications/Install\ macOS\ [macOS VERSION NAME].app/Contents/Resources/createinstallmedia --volume /Volumes/[USB DRIVE NAME]
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Replace [macOS VERSION] with the version name you have downloaded, and replace [USB DRIVE NAME] with the name of the external drive you are making bootable.
eg:

sudo /Applications/Install\ macOS\ Ventura.app/Contents/Resources/createinstallmedia --volume /Volumes/untitled
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This will also take a while, but once it has finished, you will now have an external drive you can boot from!

To boot from an external drive, you will need to boot to the boot option screen and select the drive you just created.

To get to the boot option screen:
Intel Mac - Restart Holding down the Option key.
Apple Silicon -Shut down the computer, then press and hold the power button.


Reference
https://support.apple.com/en-us/HT201255

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