NOTE: Beginning with High Sierra (MacOS 10.13) Apple does NOT permit a surface scan of the boot drive.
Well, that's a pain....I'm 10.13.6. I suppose that's the reason I get "dd: /dev/rdisk1: Operation not permitted". I wonder what the logic is behind a surface scan prohibition.
On the downside I suppose I just have to wait and see if the world comes to an end but, on the upside, I save a hundred bucks by not having to buy TechTool 11.
