How to Convert MacOS Installer to ISO

How to Convert MacOS Installer to ISO

Advanced Mac users might want to convert the MacOS Installer application to an ISO file. Usually the resulting ISO file installer is used to install macOS to a virtual machine such as VMWare or VirtualBox, but they can also be used to burn ISO to media to create a boot disk. It offers an alternative to making a bootable USB flash drive for MacOS installers as well.

This tutorial will discuss the steps to create an ISO file from the MacOS installer.

In this particular search, we will convert the MacOS Mojave installer application to an ISO file. You can use the same steps to create ISO files from almost all other MacOS Installers by presenting installmedia media, including building MacOS Catalina ISO, or for Big Sur, High Sierra, and Sierra, just by changing the appropriate file name.

How to Make a MacOS Mojave ISO or Catalina ISO File from the Installer

This process will take the installer for macOS and create an ISO file from it that can be booted or used as an ordinary disk image file.

  1. First, download the MacOS Mojave installer, or the MacOS Catalina installer (or the installer that you want to convert to ISO) from the Mac App Store
  2. When the “Install MacOS” or “Install MacOS” application is fully downloaded and in the folder / Application, continue
  3. Next, open the Terminal application
  4. Create a disk image buy DMG file by issuing the following command:

hdiutil create -o /tmp/Mojave -size 8500m -volname Mojave -layout SPUD -fs HFS+J

5. Install the DMG disk image created as follows:

hdiutil attach /tmp/Mojave.dmg -noverify -mountpoint /Volumes/Mojave

6. Next we will use createinstallmedia to create the macOS application installer on the installed volume:

sudo /Applications/Install\ macOS\ --volume /Volumes/Mojave --nointeraction

7. When making installmedia is complete, then you can delete the volume that you just created:

hdiutil detach /volumes/Install\ macOS\ Mojave

8. Now we convert the DMG disk image file to an ISO disk image file (technically the CDR file but the same iso)

hdiutil convert /tmp/Mojave.dmg -format UDTO -o ~/Desktop/Mojave.cdr

9. Finally, we renamed the CDR to ISO file extension to convert CDR to ISO:

mv ~/Desktop/Mojave.cdr ~/Desktop/Mojave.iso

That’s all, now you need to have the “Mojave.iso” disk image file on the Mac desktop which is a macOS ISO image installer.

If you intend to use an ISO file for a virtual machine, you only need to select the Mojave.iso disk image in the virtual machine application as a boot disk, or install it in a VM like other disk images. You can also convert an ISO file to a VirtualBox VDI image if needed.

ISO files are flexible and widely used, they can also be burned to create boot disks and to other media, and you can also copy the ISO to a USB drive with dd or perform many other actions.

Whether creating an ISO macOS installer file and using ISO is easier than just using a fully bootable USB flash drive is a matter of use case, and in some situations ISO is the only format that can be used (ie for certain virtualization scenarios).

Have you successfully created an ISO file from the macOS installer? Do you have another approach for creating an ISO file for the MacOS installer? Let us know in the comments below.

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