Script to automatically UNMOUT all disks EXCEPT Booting Disk

Question

The following script works directly as "AppleScript Editor" script or application (without any extra modification required) to automatically unmount the "Macintosh HD" disk after booting from other external disk:
set volname to "Macintosh HD" -- # name of target volume 
set p to (POSIX path of (volname & ":" as alias))'s text 1 thru -2
set sh to "diskutil umount " & quoted form of p & " &> /dev/null &"
do shell script sh
How to modify it (or create a new one from scratch) to unmount all disks (except the booting one, of course), whatever their names and number?
Better if the script does not issue any confirmation or warning of any kind, but works in the background without any feedback to the user.
That is great to automatically unmount ALL disks (except the booting one) after rebooting or booting, saving energy, heat, noise and speeding up the Mac performance (eg., when selecting save as, etc, since such unused disks do not show), extending the life of the unused disks.
Of course, any disk can be later on manually mounted using the Disk Utility at any time, if required.
Thanks.

Answer 1

You shouldn't make assumptions about what the names of the volumes are - both the Finder and System Events have terminology to determine if a disk is the startup volume (or a local volume, for that matter), for example:
tell application "System Events"
  repeat with someDisk in (get disks whose startup is false and local volume is true)
    set someDisk to POSIX path of someDisk
    do shell script "diskutil umount " & quoted form of someDisk & " &> /dev/null &"
  end repeat
end tell
Note that if you are unmounting a disk from a standard account you will be prompted for administrator authentication.