hdiutil detach /Volumes/Install\ macOS\ Catalina
# Convert the DMG to ISO (Desktop) hdiutil convert /tmp/Catalina.dmg -format UDTO -o ~/Desktop/Catalina.cdr macos catalina iso
An (often referring to a disk image) is a single file that contains an exact copy of a disc or file system. In the context of macOS, an ISO or DMG file allows you to: macos catalina iso
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/Catalina --nointeraction macos catalina iso
There are two ways to obtain the file: downloading it from Apple and converting it yourself, or downloading a pre-made ISO from a reputable archive.
🚀 You now have a verified, official ISO file on your desktop. Downloading a Pre-Made ISO
If not available, you can still download it using this terminal command (works as of 2025):