Typically the resulting installer ISO files are used for installing macOS into virtual machines like VMWare or VirtualBox, but they can also be used to burn the ISO to media to create a boot disk.

This offers an alternative to creating a bootable USB flash drive for MacOS installers as well.

You can use the same steps to create an ISO file from practically any other MacOS Installer with createinstallmedia present however, including building a MacOS Catalina ISO, or for Big Sur, High Sierra, and Sierra, simply by replacing the file names where appropriate.

You can also convert ISO files to VDI VirtualBox images if needed.

However, this one (How to Convert a MacOS Installer to ISO) is beyond me.

This is common practice in technical and scientific articles to help the readers.

You can create an image, partition it and put a filesystem in it, in the right image format, all in one step: hdiutil create -size 10g -type UDTO -layout SPUD -fs JHFS Desktopsomething.cdr open Desktopsomething.cdr.

Thats itunmount the new installer, rename the cdr to an iso, and youve finished.

You might want to check your mask, it may be too tight:) Thanks for the article.

How To Convert A Dmg To Iso On Mac