Apple includes a hidden tool within every macOS installer specifically designed for creating bootable drives. You’ll need to run this via Terminal (found in /Applications/Utilities).
Sometimes, the DMG you have is already a bootable image . This often happens with older macOS versions (Lion, Mountain Lion, Mavericks) or custom recovery DMGs. In this case, you don't need an installer app; you write the DMG directly to the USB. create mac os x bootable usb installer from dmg
Once the .app file is safely in your main Applications folder, we can proceed. Apple includes a hidden tool within every macOS
Always use createinstallmedia when possible. Only use dd if you have a legacy bootable DMG (e.g., OS X Lion recovery disk). you don't need an installer app
