create bootable diskimage
Best tool to create bootable disk image? For High Sierra.
Mac Pro, OS X 10.11
What you need to create a bootable installer
- USB flash drive or other secondary volume with at least 14GB of available storage, formatted as Mac OS Extended.
- Installer for OS X El Capitan or later. To get the full installer, your Mac must be using the latest version of OS X El Capitan, the latest version of macOS Sierra, or any later version of macOS. Download from a Mac that is compatible with the macOS you're downloading. Enterprise administrators: download from Apple, not a locally hosted update server.
Use Terminal to create the bootable installer
High Sierra
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
Create a bootable installer for macOS - Apple Support