Download macOS ISO

Step 1: On a Mac, start by downloading gibMacOS from GitHub. Extract the contents of the downloaded .zip file and enter the folder.

Step 2: Enter the extracted directory and double-click the gibMacOS.command file

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Since we are running a script, the file may not open right away. Open the security settings window and allow the file to run after opening it for the first time.

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When the file opens, if prompted, choose **yes (Y)** to install **Python**.

Step 3: Once the script finishes installing Python, you will see a screen in the terminal asking which version of macOS you want to download. In this example, macOS Sequoia 15.7.1 is used, so option 7 will be selected.

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Write down the size of the file you are going to download. Later, we will create an image based on this file, and it must be larger than the downloaded file.

Step 4: Once the download is complete, go to the created folder. If you ran the file from the Downloads folder, the path will look like this: ~/Downloads/gibMacOS-master/macOS Downloads/publicrelease/093-52107-15.7.1 macOS Sequoia (24G231)/ Your version numbers may be different. Inside this folder, double-click InstallAssistant.pkg and follow the instructions. This will install the application needed to build the ISO image compatible with Proxmox.

Step 5: Now we will build the ISO image for Proxmox. In a new terminal window, create a temporary disk image. Make sure it is larger than the downloaded image. For macOS Sequoia 15.7.1, a 20GB image worked.

hdiutil create -o /tmp/macOS -size 20000m -volname macOS -layout SPUD -fs HFS+J

Step 6: Mount the temporary image you just created.

hdiutil attach /tmp/macOS.dmg -noverify -mountpoint /Volumes/macOSISO

Step 7: Use the program installed earlier to create the ISO image compatible with Proxmox. This will take a few minutes.

sudo /Applications/Install\ macOS\ Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/macOSISO --nointeraction

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Make sure the path matches the exact version you installed. In this case, the file is called `Install macOS Sequoia.app`, so the path is `/Applications/Install\ macOS\ Sequoia.app/` If you installed a beta, for example, it might be: `/Applications/Install\ macOS\ Ventura\ beta.app/`

Step 8: Unmount the image using the following command:

hdiutil detach -force /Volumes/Install\ macOS\ Sequoia

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If you follow this guide exactly, you can copy and paste the command. If you use a different version, verify the correct path from Finder.

Step 9: Convert the unmounted image into an ISO file to upload to Proxmox.

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

Step 10: Change the extension from .cdr to .iso.

mv ~/Desktop/macOS-Sequoia.cdr ~/Desktop/macOS-Sequoia.iso

Step 11: Finally, remove the temporary image.

rm /tmp/macOS.dmg