The easiest way to do this is to press Command-Space Bar to open Spotlight, then type in “terminal” (without the quote marks)and press enter.

Find the file named “createinstallmedia” (see image above).

The “createinstallmedia” file is critical to this process

You’ll see the many files that make up the Resources folder: Right-click, select “Show Package Contents” Right-click on the downloaded installer application (“Install macOS Sierra Public Beta”), then select Show Package Contents (see image below).How to re-download the macOS Sierra Public Beta installer file Once the file is downloaded (it’s about 5 GB in size), make sure you know where it is (hint: it should be in your Applications folder). Note that if you have already installed Sierra on a Mac, you won’t be able to find the installer! However, you can re-download it by launching the Mac App Store, clicking on “Purchased”, finding the installer, and then clicking the Download button (see image below). The downloaded “macOS Sierra Public Beta” file.The OWC Dual USB Flash Drive or LaCie Porsche Design USB 3.0 Drive is perfect for this! Be sure that it’s erased and plugged into your Mac, and that it is visible on your Mac desktop. Note that this can be a USB flash drive, a small external hard disk drive or solid-state drive it makes no difference.

A USB drive (preferably USB 3.0) with a capacity of at least 8GB.

This can be useful in enterprise situations, where it may be advantageous to determine ahead of time which devices will be able to take advantage of macOS Sierra and which may need to be repurposed. Today we’re going to show you how to make a macOS Sierra USB installer drive in case you wish to install the beta operating system onto multiple Macs. During the past week or so, the Rocket Yard has brought you a pair of articles about macOS Sierra’s early beta test features and how to install the public beta version of the operating system.

Mac os high sierra usb installer