Extract ISO image from macOS Somona installer

macos-iso.md

Extract ISO Image from a macOS installer

Step 1

Download macOS Installer (InstallAssistant.pkg). Here is the link to Sonoma beta installer:

https://swcdn.apple.com/content/downloads/14/54/042-41491-A_WCZEM7L2US/b5eeeylcnmf82ycto51pvy0klcyzd02on8/InstallAssistant.pkg

Step 2

Run InstallAssistant.pkg by double-clicking on it. This will move Install macOS Sonoma beta.app to /Applications folder.

Step 3

Create a new DMG file, open Terminal and run:

hdiutil create -o /tmp/Somona -size 16000m -volname Somona -layout SPUD -fs HFS+J

The above command will create a 16GB DMG file called Somona in /tmp folder

Step 4

Mount the DMG file we just created:

hdiutil attach /tmp/Somona.dmg -noverify -mountpoint /Volumes/Somona

Step 5

Use createinstallmedia to create the macOS installer on the mounted volume:

sudo /Applications/Install\ macOS\ Sonoma\ beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Somona

Step 6

Unmount the volume we've just created:

sudo hdiutil detach /Volumes/Install\ macOS\ Sonoma\ beta

Step 8

Convert the DMG disk image file to an ISO disk image file (technically a CDR file):

sudo hdiutil convert /tmp/Somona.dmg -format UDTO -o ~/tmp/Somona.cdr

Step 9

Finally rename the CDR file to ISO:

sudo mv ~/tmp/Somona.cdr ~/tmp/Somona.iso

Links & Resources

https://macpaw.com/how-to/create-iso-file

https://osxdaily.com/2020/07/20/how-convert-macos-installer-iso/

June 10 2024 update:

Step 3 now requires 16250m instead of 16000m to fit the macOS 15 Sequoia beta

Here is the updated tutorial:

Extract ISO Image from a macOS installer

Step 1

Download macOS Installer (InstallAssistant.pkg). Here is the link to Sequoia beta installer:

https://swcdn.apple.com/content/downloads/50/33/052-49060-A_SUZPTRSXUG/rshd6um52uzcxnr1u85utqhl124vmsph1c/InstallAssistant.pkg

Step 2

Run InstallAssistant.pkg and go through the installeer. This will move Install macOS 15 beta.app to /Applications folder.

Step 3

Create a new DMG file, open Terminal and run:

hdiutil create -o /tmp/Sequoia -size 16250m -volname Sequoia -layout SPUD -fs HFS+J

The above command will create a 16GB DMG file called Sequoia in /tmp folder

Step 4

Mount the DMG file we just created:

hdiutil attach /tmp/Sequoia.dmg -noverify -mountpoint /Volumes/Sequoia

Step 5

Use createinstallmedia to create the macOS installer on the mounted volume:

sudo /Applications/Install\ macOS\ 15\ beta.app/Contents/Resources/createinstallmedia --volume /Volumes/Sequoia

Step 6

Unmount the volume we've just created:

sudo hdiutil detach /Volumes/Install\ macOS\ 15\ beta

Step 8

Convert the DMG disk image file to an ISO disk image file (technically a CDR file):

sudo hdiutil convert /tmp/Sequoia.dmg -format UDTO -o ~/Sequoia.cdr

Step 9

Finally rename the CDR file to ISO:

sudo mv ~/Sequoia.cdr ~/Sequoia.iso

Links & Resources

https://macpaw.com/how-to/create-iso-file

https://osxdaily.com/2020/07/20/how-convert-macos-installer-iso/

It is also recommended to use some kind of virtual Mac for this if you don't have a real Mac.