While macOS Catalina is slowly fading into legacy status, having an ISO file is essential for retro-computing enthusiasts and developers maintaining older software. By creating the ISO yourself via Terminal, you ensure you have a clean, safe, and functional copy of macOS 10.15 for years to come.
If you previously downloaded Catalina, find it in: macos catalina iso
hdiutil attach /tmp/Catalina.dmg -noverify -mountpoint /Volumes/Catalina While macOS Catalina is slowly fading into legacy