[arch-general] systemd and local group membership

Tom Gundersen teg at jklm.no
Sun Oct 28 13:37:35 EDT 2012

On Sun, Oct 28, 2012 at 12:29 PM, Giorgio Lando <giorgio.lando at gmail.com> wrote:
>> "Note: Adding your user to groups (optical, audio, scanner, ...) is not
>> necessary with systemd. It might even break the wanted functionality if
>> you do so."
> While I ignore the technical reasons, my scanner does not work if I am not
> in the scanner group.

That is a bug (or potentially a misconfiguration, though I cannot
imagine exactly how).

The way it should work is:

The udev rules shipped with sane (53-sane.rules) will make the scanner
group the owner of your scanner device and add an environment variable
for the device:  "ENV{libsane_matche}=yes" to the udev db. Based on
this variable, the rules shipped with logind (70-uaccess.rules) will
add the "uaccess" tag to the udev db for the scanner device.

That tag is what tells logind which devices to assign ACL's to (as
described by Zeke earlier in this thread).

If you are having a problem with this, please open a bug report,
making sure that you are running systemd, that your user session is
registered and considered active by logind (use loginctl to check) and
that sane is installed. Attach the output of "udevadm info /dev/<your
scanner>" to the bug report.



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