Creating a Mac OS X bootable USB installer from a DMG file involves a few simple steps:
Double-click the .dmg file to mount it. If it contains a .pkg file, run it; this typically installs a "Install macOS [Version Name]" application into your Applications folder. create mac os x bootable usb installer from dmg
A .dmg is a disk image, not the installer itself. Double-click the .dmg file to mount it. Inside, you will usually find the actual app (e.g., Install macOS Monterey.app ). For the Terminal command to work, this app must be moved into your folder. 3. Use the 'createinstallmedia' Command Creating a Mac OS X bootable USB installer