In today’s post, I will show you how to create a Mac OS High Sierra ISO file. It is useful to have around if you do not want to re-download the Mac OS High Sierra installer from the internet again in order to re-install the Operating System.
a) This can only be done on a Mac System.
b) This guide assumes you already downloaded the Mac OS High Sierra Installer from the App Store.
1) Open up the “Terminal” Application.
2) With Terminal open, type in the following command and press Enter to create the Media File.
hdiutil create -o /tmp/HighSierra.cdr -size 5500m -layout SPUD -fs HFS+J
3) Type in the following command and press Enter to mount the Media File you just created.
hdiutil attach /tmp/HighSierra.cdr.dmg -noverify -mountpoint /Volumes/install_build
4) Type in the following command and press Enter to start building the Install Media.
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/install_build
Input the Password to the account you are logged in.
At this prompt, type in “Y” and then press Enter.
Wait for the Copy of the Installation files to finish.
5) Type in the following command and press Enter to move the Installation Image to your Desktop.
mv /tmp/HighSierra.cdr.dmg ~/Desktop/HighSierra.dmg
6) Type in the following command and press Enter to detach the installation image that is currently mounted.
hdiutil detach /Volumes/Install\ macOS\ High\ Sierra
7) Type in the following command and press Enter to convert the DMG file to a ISO file.
hdiutil convert ~/Desktop/HighSierra.dmg -format UDTO -o ~/Desktop/HighSierra.iso
8) You will now have the Mac OS High Sierra ISO file on your Desktop. It will have a .CDR file extension but you can manually rename it to a .ISO extension.
I hope this post has been helpful! 😀