Actually I ran it with sudo (I was root)... And the same error (unable to open device) happens when I run it with a regular user, or using sudo...
I have also notice that there is no such directory, (/sys/devices/pci0000:00/0000:00:1d.7/usb2/2-4/2-4:1.0/host12/target12:0:0/12:0:0:0/block/sdb/sdb1) but that there is another one that exists (/sys/devices/pci0000:00/0000:00:1d.7/usb2/2-4/2-4:1.0/host20/target20:0:0/20:0:0:0/block/sdb/sdb1).
Actually I ran it with sudo (I was root)... And the same error (unable to open device) happens when I run it with a regular user, or using sudo...
I have also notice that there is no such directory, (/sys/devices/ pci0000: 00/0000: 00:1d.7/ usb2/2- 4/2-4:1. 0/host12/ target12: 0:0/12: 0:0:0/block/ sdb/sdb1) but that there is another one that exists (/sys/devices/ pci0000: 00/0000: 00:1d.7/ usb2/2- 4/2-4:1. 0/host20/ target20: 0:0/20: 0:0:0/block/ sdb/sdb1) .
Not sure if it is helpful.