is there a way to eject all external hard drives from the command line? (OS X)

Question

Is there a way to eject all the mounted hard drive volumes on an OS X computer from the command line? Applescript is OK if I can wrap that in a shell script.

Answer 1

I found this to work for ejecting all dmg and physical hard drives:

find /dev -name "disk[1-9]" -exec diskutil eject {} \;