: You will need approximately 8.5 GB of free space to download the installer.
: Apple provides .dmg files for individual updates (like the Catalina 10.15.7 Update ), but these require a version of Catalina to already be installed and are not full OS installers. Creating a DMG from the Installer Download Macos 10.15 Catalina Dmg File
hdiutil create -o /tmp/Catalina -size 8500m -volname Catalina -layout SPUD -fs HFS+J : You will need approximately 8