How To Download MacOS Mojave Installer And Convert To ISO File

This article will tell you how to download the macOS Mojave installer file to your Mac, and how to convert the installer file to an iso file. Then you can use the iso file to install macOS on a virtual machine.

1. Download macOS Mojave.

1. Open mac App Store on a mac machine.
2. Then search the keyword Mojave in the left search text box.
3. Click the download icon ( cloud icon ) in the right panel to download the macOS Mojave installer.
4. After download, the macOS Mojave installer dialog will be prompt, just click the menu item Install macOS Mojave —> Quit Install macOS to quit the install dialog.
   
5. The installer file will be saved in the Applications folder, and the installer name is Install macOS Mojave.
   
6. Right-click Install macOS Mojave application in Finder, then click Show Package Contents menu item in the popup menu list to list the Contents folder of Install macOS Mojave application. You will also see the SharedSupport folder and BaseSystem.dmg file. This file will be used to create the iso file later.
   
7. You can also goto the above directory in a terminal use the cd command to verify the folder is exist.

   $ cd /Applications/Install\ macOS\ Mojave.app/Contents/SharedSupport/
   $ pwd
   /Applications/Install macOS Mojave.app/Contents/SharedSupport

2. Create macOS Mojave Installer ISO File.

After download the macOS Mojave installer, it is time to create the iso file for it.

1. Open a terminal and run the hdiutil create command to create a blank temporary disk image.

   $ hdiutil create -o /tmp/MoJave.cdr -size 7316m -layout SPUD -fs HFS+J
   created: /tmp/MoJave.cdr.dmg

2. Mount above blank temporary image to the installer volume use hdiutil attach command.

   $ hdiutil attach /tmp/MoJave.cdr.dmg -noverify -nobrowse -mountpoint /Volumes/install_build
   /dev/disk3          	Apple_partition_scheme         	
   /dev/disk3s1        	Apple_partition_map

3. Restore the installer’s BaseSystem.dmg to the above mounted-image use asr restore command.

   $ asr restore -source /Applications/Install\ macOS\ Mojave.app/Contents/SharedSupport/BaseSystem.dmg -target /Volumes/install_build -noprompt -noverify -erase
     Validating target...done
     Validating source...done
     Retrieving scan information...done
     Validating sizes...done
     Restoring  ....10....20....30....40....50....60....70....80....90....100
     Restored target device is /dev/disk3s2.
     Remounting target volume...done

4. Unmount the temporary image use hdiutil detach command.

   $ hdiutil detach /Volumes/macOS\ Base\ System/
   "disk3" ejected.

5. Now you can use hdiutil convert command to convert the above image to the iso file that you want.

   $ hdiutil convert /tmp/MoJave.cdr.dmg -format UDTO -o /tmp/MoJave.iso
   Reading Driver Descriptor Map (DDM : 0)…
   Reading Apple (Apple_partition_map : 1)…
   Reading disk image (Apple_HFS : 2)…
   ....................................................................................................................................................................................
   Elapsed Time: 33.626s
   Speed: 217.6Mbytes/sec
   Savings: 0.0%
   created: /tmp/MoJave.iso.cdr
   

6. Rename the created MoJave.iso.cdr file to MoJave.iso and move it to the desktop.

   $ mv /tmp/MoJave.iso.cdr ~/Desktop/MoJave.iso

7. Now you can copy the iso file to a USB disk to install it on a virtual machine.