On 01 Oct 10:58, Ian Thompson-Bell wrote:
In the past I have found the easiest way to resolve permissions with sane is to log in as root and try scanning. Usually that works which confirms it is simply a permissions problem.
sane will also complain that you're root, ask if you're absolutely sure you want to do this, and warn you that if it kills your cat it's your own silly fault...
For a case of just looking at the permissions that the device has in /dev/bus/usb...
E.g. on this laptop I have a (working) finger print scanner, relevant line from lsusb: Bus 002 Device 002: ID 08ff:2580 AuthenTec, Inc. AES2501 Fingerprint Sensor
Permissions on the device: $ ls -la /dev/bus/usb/002/002 crw-rw-r-- 1 root plugdev 189, 129 Oct 1 11:14 /dev/bus/usb/002/002 $
Oh, look, that's read and writable by root and the plugdev group... so, what groups am I in? $ id uid=1000(brettp) gid=1000(brettp) groups=1000(brettp),20(dialout),24(cdrom),25(floppy),29(audio),44(video),46(plugdev),109(fuse),1002(sbox) $
Oh look, I'm in the plugdev group, so I have read/write on the fingerprint scanner! Well, that's handy... (given that I use it to auth to xscreensaver... along with a password fallback).
Permissions are *not* complicated, *are* central to the operation of a linux machine, and should be got to grips with early on.
If I hadn't been in the group then I'd have done: sudo adduser brettp plugdev
Which would have added me in to the group, I'd have then logged out and back in again to make sure that the group membership had taken, and then tried again.
This ain't rocket science. Use root *very* sparingly and always remember that running *anything* as root is a security risk.
Cheers,