Creating a Multi-OS Installer Flash Drive

As an IT support specialist, I provide services to a wide range of corporate and private clients. One of my most popular activities is installing operating systems (OS) on Mac and Windows computers. As a result, I tend to carry around multiple bootable flash drives, each containing the installer for a different operating system. This includes different versions of macOS, Windows, and Linux distributions.

I recently decided that it would be much more efficient if I could put all the different operating systems I need on one flash drive. So I created a drive that holds multiple versions of macOS and Windows 10. The drive is created on a Mac running macOS Big Sur, but can run on a Mac or Windows computer. It can then be used to install macOS or Windows 10 on a Mac or Windows 10 on a PC.

Read on to learn how to create a multi-OS installation flash drive using a Mac.

Prepare the flash drive

The first stage in the process is to prepare the flash drive that you will use by erasing and formatting it. Here are the necessary steps.

  1. select utilities IN Search Engines and open Disk Utility.
  2. Connect your flash drive and check it Show all devices marked in See menu in Disk Utility.
  3. You should see your flash drive listed below Outside in the left pane Disk Utility. Click it and then click Delete.

  1. Give it a drive Name (I call him Operating systems) and select Mac OS Extended (registered) EQUAL Format And GUID Partition Map EQUAL Mechanism.

  1. Click Delete.
  2. When the deletion is complete, click Finished.

Burn the first version of macOS to a Flash drive

You are now ready to write your first macOS flash drive installer. Let’s start with the latest version, which is macOS Big Sur.

The first step is to download the macOS Big Sur installer. Apple has made this pretty easy, and the page contains download links for all recent versions of macOS, along with instructions on how to create a bootable installer. Press only macOS Big Sur Under the title Download macOS. This will take you to the App Store where you can simply click TAKE. After a few seconds, you will be asked if you are sure you want to download macOS Big Sur and you should click Download file.

Once the download is complete, you can eliminate any attempt to start the macOS installation. It is important that your installer is now downloaded Applications map. that’s called Install macOS Big Sur.

To burn the installer to the desired partition on your flash drive, open End which you will find in utilities IN Search Engines. Then type the following command.

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sudo /Applications/Install\ macOS\ Big\ –volume /Volumes/OperatingSystems

This command will be different if you are writing a non-Big Sur version and you should check the correct syntax under the heading Use “createinstallmedia” command in terminal on the How to Create a Bootable Installer for macOS page. Another possible component would be the following episode name /Practice that was in my case Operating systems.

After you press input you will be prompted for the administrator password. You will then need to confirm that you want to continue and the operation will continue. This will take some time, depending on the speed of your flash drive, and you should see a progress from 0 to 100% as the files are copied to the drive.

You now have a bootable flash drive containing the macOS Big Sur installer. You are now ready to continue adding additional macOS installers to the drive.

Disk partition

First you need to partition the drive.

Return plate Utility and click on your flash drive in the left pane. You will see that under the drive name there is now the name of your first volume, which is Install macOS Big Sur.

Click bulkhead and you will see a partition window. In this window, you can define the partitions you need, along with their sizes.

For now, let’s create an additional partition that we will use to install macOS Catalina.

Click + create an additional partition and then give it a Name. The Format it should Mac OS Extended (registered) as before Size 12 GB is enough.

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Click apply when you’re ready, click to confirm bulkhead in the next window. The operation will take a while and then you will see a window saying the operation was successful. Click Finished to remove the window.

You can now download the macOS Catalina installer the same way you did for Big Sur. Then come back End and enter a command similar to the one used for Big Sur, but change the name of the installer and the name of the target drive. In this case, it will be the next command.

sudo /Applications/Install\ macOS\ –volume /Volumes/macOSCatalina

Re-enter your admin password, confirm that you want to continue, and the operation will continue.

You now have a bootable flash drive with two partitions containing installers for different versions of macOS. You can then proceed with the process of creating new partitions, downloading the desired installers and burning them to a flash drive. Apple provides instructions for the most distant versions OS X El Capitan and you won’t need an older version than this unless you’re running a very old Mac.

Add partition Windows 10

Now we will add a Windows 10 installation partition to the drive.

Return Disk Utilityclick on your flash drive and select bulkhead again. This time add a partition named 10 . windowwith the format MS-DOS (US) and 8 GB in size.

Click apply And after that bulkhead as before.

Now you need to download the Windows 10 ISO file (installer) from Microsoft. You can do this by going to their page to download the Windows disk image (ISO file). For the purposes of this tutorial, I’m assuming you’re downloading the 64-bit international English version. Once you have downloaded the file, write down its full name in Download map. Then come back End and type the following command to mount the downloaded ISO file.

hdiutil mount ~/Downloads/

Then open it Disk Utility and note the name of the disk image you just created, below Disk image.

Now you have to go back End and type the following command.

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rsync -avh –progress –exclude=sources/install.wim /Volumes//* /Volumes/W10

Now you need to install a package manager called Homebrew. To do this, use the following command End.

/bin/bash -c “$(curl -fsSL”

You will need to enter your administrator password and confirm the operation. Once it is installed, type the following command.

brew install wimlib

Finally, enter the following command to burn the Windows 10 installer to the Windows partition on the flash drive.

split wimlib-imagex /Volumes//sources/install.wim /Volumes/W10/sources/install.swm 3800

Check the installer

To check if your flash drive is working properly, first turn off your computer. Then start the computer with the flash drive connected and hold the . key select key when it starts. After a short while, you will see all the boot options available to you. The first will be your Mac’s hard drive, then you’ll see any versions of the macOS installer you installed on the flash drive, as well as the Windows installer, named, start EFI. Clicking on any of them will launch the respective installer, allowing you to proceed with the installation of that operating system.


As an IT support professional, having a macOS installer, along with a Windows 10 installer, on the same flash drive is invaluable. Although we created the drive using a Mac, it can also be used to install Windows 10 on a Windows PC.

Gone are the days when we had to carry around multiple USB flash drives.

Categories: How to

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