How to Create a macOS Big Sur ISO File Using Terminal

Jan. 12, 2021



There is more than one reason why you may want to create a macOS Big Sur ISO file. Maybe you wish to install macOS intovirtual machinessuch as VMWare and Parallels Desktop for extensive testing. Maybe you are willing to make an alternative installer media on an external hard drive. Whatever could be your reason for making a macOS Big Sur ISO file, you would be glad to know it’s possible to fine-tune a fully functional ISO file without having to use any third-party tool. If you are all set, let me guide you through!

Make a macOS Big Sur ISO File Using Terminal App

Make a macOS Big Sur ISO File Using Terminal App

So, how do you get an ISO file on Mac? Thanks to the built-in app called Terminal, you can make a workable ISO file through the command line. For the folks who are wondering as to why the entire process requires the need of Terminal or a third-party app, it is because the macOS installer application is actually an .app file (and not a disk image).

It’s worth pointing out that you can use the same process to create ISO file for the previous generations of macOS likemacOS Catalinaand Mojave as well. So, even if you want the file for the older generations of macOS, the following steps can take you through. With that said, let’s get going!

  1. Now, open theTerminalapp. You can launch it from theApplications > Utilitiesfolder. Alternately, you can pressCommand+Spaceand search for theTerminal appto quickly find it.

  2. Next, it’s time tocreate a temporary disk image. Launchterminal and run the following command.

  3. Next up, you need tomount the disk image:

  4. Up next,copy the installer filesto the disk image we have just created using the createinstallmedia utility which is part of the macOS Installer application.

  5. Now,press returnand then type theadmin passwordto authenticate. Now, you need to wait for some time until the installer is created.  Once the process is completed, you will need tounmount the disk imagevolume.

  6. Next,convert the newly created macOS Insaller disk image fileto an ISO/CDR file. Now, it will show up on the desktop.

  7. Next up,change the file extensionfrom .cdr to .iso.

That’s all there is to it! You have successfully made a macOS Big Sur ISO file (named as BigSur.iso) on your Mac.

So, that’s how you can create a functional ISO file using the Terminal app on your Mac. It’s good that the first party app works reliably in making an ISO file as you don’t have to look for third-party software or even dole out some bucks. As someone who heavily relies on Terminal for getting it done, I must say that you can count on the app to live up to the task more often than not.

Though it’s also possible to convert dmg and CDR files to ISO with the help of Disk Utility, the whole process doesn’t feel straightforward. Therefore, I don’t recommend it. By the way, have any questions or feedback? Be sure to put your thoughts across related to this topic. Also, don’t forget to read our coverage of other articles on macOS Big Sur, including our collection of bestBig Sur widgets,solving battery drain issues on Big Sur, and more.

An old school bibliophile who turned a tech nerd out of obsession. When he is not digging into hacks and tracking down stories that are breaking the internet, you may find him reciting poems.

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