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How to create a bootable ISO image for a macOS installer

Published: 26 April 2020
Filed Under: macOS

There are a few uses for creating a bootable ISO image of a macOS installer, including for those who want to run macOS as a guest virtual machine in either VirtualBox or VMware. You'll need to have at least 18 GB of free disk space, and the correct macOS installer already downloaded. Once you're ready, run the correct command for your choice of operating system below and the final ISO will be placed in your home directory.

macOS 10.15 Catalina

hdiutil create -o /tmp/Catalina -size 8500m -layout SPUD -fs HFS+J -volname Catalina
hdiutil attach /tmp/Catalina.dmg -noverify -mountpoint /Volumes/Catalina
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Catalina
hdiutil detach /volumes/Install\ macOS\ Catalina
hdiutil convert /tmp/Catalina.dmg -format UDTO -o Catalina.iso
mv /tmp/Catalina.iso.cdr ~/Catalina.iso
rm /tmp/Catalina.dmg

macOS 10.14 Mojave

hdiutil create -o /tmp/Mojave -size 8500m -layout SPUD -fs HFS+J -volname Mojave
hdiutil attach /tmp/Mojave.dmg -noverify -mountpoint /Volumes/Mojave
sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia --volume /Volumes/Mojave
hdiutil detach /volumes/Install\ macOS\ Mojave
hdiutil convert /tmp/Mojave.dmg -format UDTO -o Mojave.iso
mv /tmp/Mojave.iso.cdr ~/Mojave.iso
rm /tmp/Mojave.dmg

macOS 10.13 High Sierra

hdiutil create -o /tmp/HighSierra -size 8500m -layout SPUD -fs HFS+J -volname HighSierra
hdiutil attach /tmp/HighSierra.dmg -noverify -mountpoint /Volumes/HighSierra
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/HighSierra
hdiutil detach /volumes/Install\ macOS\ High\ Sierra
hdiutil convert /tmp/HighSierra.dmg -format UDTO -o HighSierra.iso
mv /tmp/HighSierra.iso.cdr ~/HighSierra.iso
rm /tmp/HighSierra.dmg