How to create a bootable Mac OS install drive

I have been struggling with using the internet install for a few days due to my current unreliable ISP (internet service provider), rain — SA’s mobile data-only network | Fast, affordable internet. There is nothing reliable and fast about their service/s.

The installation kept timing out due to the connectivity issues, so I eventually decided to down the installation image and create a bootable UBS drive to use for the installation. Downloading the images/dmg was not an easy task, at least in my experience. I couldn’t find the images/dmg anywhere in the AppStore (I only found updates and not the full installations). The trick was to do a complete search on Google and I was able to find articles on the Apple website that had direct links to the DMG files.

Download and install

Find the appropriate download link in the upgrade instructions for each macOS version:

macOS Catalina, macOS Mojave, or macOS High Sierra
Installers for each of these macOS versions download directly to your Applications folder as an app named Install macOS Catalina, Install macOS Mojave, or Install macOS High Sierra. If the installer opens after downloading, quit it without continuing installation. Important: To get the correct installer, download from a Mac that is using macOS Sierra 10.12.5 or later, or El Capitan 10.11.6. Enterprise administrators, please download from Apple, not a locally hosted software-update server.

OS X El Capitan
El Capitan downloads as a disk image. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X El Capitan into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

You can also rely on the power of Google to search and download a specific version you want, but preferably directly from the Apple website.

Use the ‘createinstallmedia’ command in Terminal

  1. Connect the USB flash drive or another volume that you’re using for the bootable installer. Make sure that it has at least 12GB of available storage and is formatted as Mac OS Extended.

Catalina installation

sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

Mojave installation

sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

High Sierra installation

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

Yosemite installation

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction

El Capitan installation

sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app

4. Press Return [Enter] after typing the command.

5. When prompted, type your administrator password and press Return [Enter] again. Terminal doesn’t show any characters as you type your password.

6. When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the bootable installer is created.

7. When Terminal says that it’s done, the volume will have the same name as the installer you downloaded, such as Install macOS Catalina. You can now quit Terminal and eject the volume.

* If your Mac is using macOS Sierra or earlier, include the --applicationpath argument, similar to the way this argument is used in the command for El Capitan.

Booting from the bootable USB

Now that you have a bootable USB, follow the following steps to use it:

  1. Plug in the bootable USB into your Mac

You now should be set and ready with a freshly installed OS on your Mac.

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