Once in a while you may want to do a clean install of macOS High Sierra, or you have multiple Macs to install it on, then a bootable flash drive for is your best bet for easy installation.

Note: This guide is based macOS High Sierra other versions has a different command for creating the bootable USB thumb drive.

Here’s how to make a bootable thumb drive.

First step is to download the sources;

On you’re mac open the App Store, and search for the macOS High Sierra download.

The next step is to create the bootable macOS installer;

On you’re mac open Terminal in order to execute the following commands.
Note: make sure you change the YOUR_USB_DRIVE to the correct name of the drive.

sudo \
/Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia \
 --volume /Volumes/YOUR_USB_DRIVE/ \
 --applicationpath /Applications/Install\ macOS\ High\ Sierra.app &&\sync

Even with a USB3 thumb drive this process could take up some time to complete, so grab a coffee  😀

The process should look something similar like this;

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia \
> --volume /Volumes/16GBUSB3/ \
> --applicationpath /Applications/Install\ macOS\ High\ Sierra.app
Ready to start.
To continue we need to erase the volume at /Volumes/16GBUSB3/.
If you wish to continue type (Y) then press return: y
Erasing Disk: 0%... 10%... 20%... 30%...100%...
Copying installer files to disk...
Copy complete.
Making disk bootable...
Copying boot files...
Copy complete.

Great the hardest part is over and you should be able to boot you’re mac from bootable thumb drive you just created.

Boot from the macOS installer;

Now the easiest part of this guide; booting from the macOS bootable installer.

  1. Make sure the USB thumb drive is connected to your mac.
  2. Restart or power-on the mac and press and hold in the Option key while the mac boots, release it when a boot menu appears.
  3. Click on the round Install macOS High Sierra icon.
    And click on the arrow to continue.
  4. Wait until the installer is fully loaded, you should see the Apple logo and an progress bar.
  5. When fully loaded you should see a macOS Utilities window.
  6. If you want to configure the disk before installing open Disk Utility otherwise click on Install macOS to begin the installation.
  7. Install macOS…

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