Step 3: Here, set the name for the flash drive we’re going with Untitled. Once the app opens, make sure that it is selected in the left section, and hit the Erase button up top. Step 2: Connect the aforementioned USB flash drive to your Mac, and then launch the Disk Utility app to format the connected flash drive. The app will be titled, “Install macOS High Sierra”. Step 1: To begin, download macOS High Sierra 10.13 installer app from the Mac App Store. Now that we have that covered, let’s proceed with the actual installation.

Approximately 15-20 minutes of your time, and of course, the ability to exercise some patience as the process completes.

The drive in question will be entirely formatted as part of the process, so if there’s any important data on it that needs to be kept, make sure it’s removed prior to beginning the process.

A USB flash drive with a recommended minimum capacity of 16GB.

You can find compatibility for High Sierra here: macOS 10.13 High Sierra Compatibility: Full List Of Macs Compatible With Apple’s Latest Desktop OS.

A compatible version of Mac running any version of OS X/macOS.

You can now quit Terminal and eject the volume.

When Terminal says that it's done, the volume will have the same name as the installer you downloaded, such as Install macOS Monterey.

After the volume is erased, you may see an alert that Terminal would like to access files on a removable volume.

Terminal shows the progress as the volume is erased.

When prompted, type Y to confirm that you want to erase the volume, then press Return.

Terminal doesn't show any characters as you type.

When prompted, type your administrator password.If the volume has a different name, replace MyVolume in the command with the name of your volume. Each command assumes that the installer is in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using.

Type or paste one of the commands below into Terminal, then press Return to enter the command.

Open Terminal, which is in the Utilities folder of your Applications folder.

Plug in the USB flash drive or other volume that you're using for the bootable installer.

Osx high sierra bootable usb