If you want to use a thumb drive, an 8GB drive works perfectly. This will allow you to connect a storage device that uses a USB type-A connector. You can also click here.
Make a Bootable Flash Installer of OS X or macOS
You can read the information to learn more about High Sierra. Once the download is complete, the installer will launch automatically. Instead, press Command-Q on your keyboard to quit the installer. The High Sierra installer app will be in your Applications folder, so you can go there and launch it later to upgrade your Mac to the new operating system. This link should open the App Store app and take you directly to High Sierra. Under the High Sierra icon on the left of the banner, click on the Download button.
This will download the installer to your Applications folder. If the installer auto launches, press Command-Q on your keyboard to quit the app. It has been updated to support High Sierra. It now does.
How to Make a Bootable Flash Installer of OS X or macOS
Download Install Disk Creator by clicking on the link above. When the download is done, you can move it over to your Applications folder. Then follow these steps to create your bootable macOS High Sierra drive. How to create a bootable macOS Sierra installer drive. The general recommendation is to skip the manual method for any version of the Mac OS that is newer than OS X Mavericks, and instead use the Terminal method and the createinstallmedia command, as outlined below.
Before you begin, stop. That may sound a bit daft, but as I mentioned above, if you use the OS X or macOS installer, it will likely delete itself from your Mac as part of the installation process. So, if you haven't yet used the installer you downloaded, don't. If you've already installed the Mac OS, you can re-download the installer following these instructions:.
If you're just now downloading the installer, you'll notice that once the download is complete, the installer will start up on its own. You can just quit the installer, the same way you'd quit any other Mac app.
A USB flash drive. I suggest a flash drive in the 32 GB to 64 GB range, as they seem to be the sweet spot in cost and performance. The actual size of the bootable version of the installer varies, depending on which version of the Mac OS you're installing, but so far, none has gone over 8 GB in size.
It's not really that much of a secret, but ever since OS X Mavericks , the Mac OS installers have contained a command hidden inside the installer package that takes what used to be a complex process for creating a bootable copy of the installer, and turns it into a single command you enter into Terminal.
Use the 'createinstallmedia' command in Terminal
This Terminal command, called createinstallmedia, can create a bootable copy of the installer using any drive connected to your Mac. The process is the same, regardless of the destination. Whatever media you use to create the bootable Mac OS installer on, it will be completely erased by the createinstallmedia command, so be careful.
Whether you're going to use a flash drive, a hard drive, or an SSD, be sure to back up any data on the drive before you begin this process. You now have a bootable copy of the OS X or macOS installer that you can use to install the Mac OS on any of your Macs, including using the advanced Clean Install method; you can also use it as a troubleshooting utility.
Share Pin Email. Tom Nelson has written hundreds of articles, tutorials, and reviews for Other World Computing and About.
He is the president of Coyote Moon, Inc. Updated December 19, If you've already installed the Mac OS, you can re-download the installer following these instructions: If it's not there, or you're not sure of its name, seethe previous section of this guide for details on the installer file name, and how to download the needed file. Plug your USB flash drive into your Mac. Check the flash drive's content.