tried with "xxd -p"
sudo dd if=/dev/sdb | xxd -p | grep [^00]
..and nothing red showed up as I want it
For getting some more trust I
tried to write a "1" onto /dev/sdb for checking again
(found on net dont know if doing right)
sudo dd if=/dev/zero bs=1 count=1 | tr "\0" "\1" > onefile
sudo dd if='/home/user/onefile' of=/dev/sdb
and now
sudo dd if=/dev/sdb | xxd -p | grep [^00]
gives a red "1"
010000000000000000000000000000000000000000000000000000000000
I used this shred on files but didnt know it works on whole drives its cool
to have it. And with good status output.
And I got onto this "dc3dd" like a better "dd" with many details.
