SD Mounts Drive but how do I unmount it when done?

[transco]

Originally Posted by dnanian

Where do you do that? In a shell script (it's not a shell script)... SD! automatically unmounts a drive, if it started unmounted, on a scheduled copy already...

Is there a shell script that automatically dismounts a drive during the initial startup procedure? The drive I am going to use for my target is an internal drive (Mac Pro) and I'd like to dismount it after the computer boots up, then leave it for SuperDuper to mount and dismount during the nightly scheduled cloning of the master boot drive.