Every official macOS installer app contains a hidden Unix binary called createinstallmedia . This is the magic wand.

You don't need to type the whole path. Type sudo (with a space), then drag the createinstallmedia file from the .app (Right-click the app > Show Package Contents > Contents > Resources) into the Terminal window. Then type --volume and drag your USB drive (MyVolume) from the Finder sidebar into the Terminal.

Once the .app file is safely in your main Applications folder, we can proceed.

Before beginning, ensure you have a USB flash drive with a minimum of to 32GB of capacity, as modern macOS installers (like Sequoia or Sonoma) exceed the standard 8GB limit. Note that the creation process will completely erase the drive, so any critical data must be backed up beforehand. 2. Method A: Using a Working Mac (Recommended)

You cannot simply copy this .app to the USB. You must extract the hidden system files inside the app.