Make a bootable copy of macOS High Sierra so you can have a portable copy to install on multiple devices.
When it comes time to upgrade your Mac operating system, the first thing to consider is whether you want to install it directly onto your Mac or create a bootable drive. You can use a bootable drive on a hard drive partition for dual-software installation, to install on multiple Macs in your home, or as a bootable drive if you can’t use the Internet Recovery partition.
Note: These instructions require the use of Terminal. If you don’t feel comfortable making changes to your Mac with Terminal, you can create a bootable disk using the DiskMaker X program.
Before you start
Before you get started, make sure you have a thumb drive with at least 8GB of storage, or a spare external hard drive (one you aren’t planning to use for anything else). You’ll also need to download macOS High Sierra from the Mac App Store.
Note: After macOS Sierra has downloaded, it will automatically launch the installer to begin the installation process. Close the installer instead.
And please: Don’t forget to back up your Mac before you do anything.
How to format your external drive for macOS High Sierra
You’ll need to start with a clean thumb drive or hard drive in order to make it a bootable drive.
- Plug the thumb drive or cable for your hard drive into the appropriate port on your Mac.
- Click on Finder in your Dock to open a Finder window.
Select Applications from the list on the left side of the window.
- Scroll down and double-click on Utilities.
Scroll down and double-click on Disk Utility.
- Select your drive under External.
Click on the…
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