Type the following command: softwareupdate --fetch-full-installer --full-installer-version 10.13.6 Press Enter and wait for the process to complete. Creating the ISO File from the Installer
(Replace MyVolume if you named your disk differently): sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/install_build macos high sierra download iso
The USB drive showed up: a bright yellow hard disk labelled "macOS High Sierra Installer." macos high sierra download iso