Tak to už jsem zkoušel.
mount /media/pi/My Passport/rasspbian-2018-05-18.img /mnt
https://www.raspberrypi.org/forums/viewtopic.php?t=54784
sudo mount -o loop,offset=$((512*8192)) /media/pi/My Passport/rasspbian-2018-05-18.img /media/raspbian
Nefunguje