The following command installs the .pkg to the local hard disk.

installer -pkg /Users/username/Desktop/package.pkg -target LocalSystem

You can also replace “LocalSystem with a “/” they both do the same thing.

If you want to install the package on a different disk you can change the -target to the drives path.

installer -pkg package.pkg -target "/Volumes/Macintosh HD2"

You can find more about the command by typing “man installer” in the terminal.