The idea is to make an ISO file so we can create a virtual machine with (for example) VMWare Fusion on my Mac that runs Ventura.
This way I can do a few tests with the older Monterey OS.
1. In the Apple Store get the Monterey Install app.
This will most likely open a window at some point wanting to install Monterey - of course we do not want to do this.
In the menu of the installer Quit the installer.
You should still see "Install macOS Monterey" in your Applications folder.
2. Run these steps, make sure you have at least app.16Gb disk space available.
sudo hdiutil create -o /tmp/Monterey -size 16g -volname Monterey -layout SPUD -fs HFS+J
sudo hdiutil attach /tmp/Monterey.dmg -noverify -mountpoint /Volumes/Monterey
sudo /Applications/Install\ macOS\ Monterey.app/Contents/Resources/createinstallmedia --volume /Volumes/Monterey --nointeraction
hdiutil eject -force /Volumes/Install\ macOS\ Monterey
hdiutil convert /tmp/Monterey.dmg -format UDTO -o ~/Downloads/Monterey
mv -v ~/Downloads/Monterey.cdr ~/Downloads/Monterey.iso
sudo rm -fv /tmp/Monterey.dmg
You could throw this in a script, if you'd like. I prefer to go through each step to see what goes wrong, IF something goes wrong.
What these steps do:
- Create a temporary disk image
- Attach the temporary disk image (mount)
- Have the Monterey Installer create install media on that temporary disk image
- Eject the temporary disk image
- Convert temporary disk image to CD/DVD format (CDR file)
- Rename the CDR image file to ISO
- Remove the temporary disk image
You should now have a Monterey ISO.