Create bootable ISO from macOS Catalina Installer

CreateBootableISOfromMacOSCatalinaInstaller.sh

# https://support.apple.com/en-us/HT201372

# download macOS Catalina
# https://itunes.apple.com/us/app/macos-catalina/id1466841314?ls=1&mt=12

# create blank image and put in /tmp directory
hdiutil create -o /tmp/Catalina.cdr -size 7000m -layout SPUD -fs HFS+J

# mount blank image at install_build
hdiutil attach /tmp/Catalina.cdr.dmg -noverify -mountpoint /Volumes/install_build

# run the createinstallmedia on the target /Volumes/install_build
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/install_build

# move populated image to Desktop and name it InstallSystem.dmg
mv /tmp/Catalina.cdr.dmg ~/Desktop/InstallSystem.dmg

# unmount Catalina install
hdiutil detach /Volumes/Install\ macOS\ Catalina

# convert dmg to iso
hdiutil convert ~/Desktop/InstallSystem.dmg -format UDTO -o ~/Desktop/Catalina.iso