Steps to create a bootable ISO image of MacOS X 10.8 Mountain Lion installer

Steps to create a bootable ISO image of MacOS X 10.8 Mountain Lion installer
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Mountain Lion seems to be so old. However, some still wants to install this outdated operating system for development purposes. Here we will show specific instruction to how to create a bootable ISO image of MacOS X 10.8 Mountain Lion installer on Mac.

DOWNLOAD
Mountain Lion is not available to download from Apple Store anymore. You can download
Mountain Lion.app from any sources from internet. We uploaded the original MacOS X 10.8.5 Mountain Lion.app here.

Creating bootable disk from MacOS X 10.8 Mountain Lion.app

hdiutil attach /Applications/Install\ OS\ X\ Mountain\ Lion.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app

hdiutil create -o /tmp/Mountain_Lion.cdr -size 6g -layout SPUD -fs HFS+J

hdiutil attach /tmp/Mountain_Lion.cdr.dmg -noverify -nobrowse -mountpoint /Volumes/install_build

asr restore -source /Volumes/install_app/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase

rm /Volumes/Mac\ OS\ X\ Base\ System/System/Installation/Packages

cp -rp /Volumes/install_app/Packages /Volumes/Mac\ OS\ X\ Base\ System/System/Installation/

cp -rp /Volumes/install_app/BaseSystem.chunklist /Volumes/Mac\ OS\ X\ Base\ System/System/BaseSystem.chunklist

cp -rp /Volumes/install_app/BaseSystem.dmg /Volumes/Mac\ OS\ X\ Base\ System/BaseSystem.dmg

hdiutil detach /Volumes/install_app

hdiutil detach /Volumes/Mac\ OS\ X\ Base\ System/

hdiutil convert /tmp/Mountain_Lion.cdr.dmg -format UDTO -o /tmp/Mountain_Lion.iso

mv /tmp/Mountain_Lion.iso.cdr ~/Desktop/Mountain_Lion.iso

If you want to download this exact iso file, go to this topic: Download all MacOS X 10.4 - 10.14 original