lcdproc - problem running as ordinary user.

prhunt · May 1, 2011, 1:23am

I’m trying to get lcdproc running on my mythtv box.

I have the LCDd daemon loading and running correctly as a start-up service.

The lcdproc client also works, but only if it is run as root. I believe that it should be able to run as an ordinary user.

Suspecting some permissions issue, I chmod’d the /dev/lcd0 device to 666. This did not fix the problem.

Some info: openSUSE 11.3 (i32) with distribution kernel. lcdproc 0.5.4 compiled from source. Using the imonlcd device.

I have also posted on the lcdproc mailing list, but am suspicious that some openSUSE-specific permission issue may be the culprit.

If any lcdproc users have had greater success, I’d like to hear from you.

Any assistance appreciated

Paul

ken_yap · May 1, 2011, 1:52am

How is the LCD connected to the computer? If through a parallel port and the program does IN and OUT instructions after doing ioperm(), then root permission is needed by the program.

Another possibility is apparmor.

prhunt · May 1, 2011, 4:26am

Hi Ken,

The LCD connects by USB. I have disabled apparmor. I made the device /dev/lcd0 everyone read and writable. Maybe I need to do something at the USB device level. I’d have thought that with the server / client framework which lcdproc employs, a userspace client would be able to operate without root privilege. Paul

martin_helm · May 1, 2011, 2:39pm

prhunt wrote:
> The LCD connects by USB.
I see you already changed the permissions on the /dev/… so this is a bit a
blind shot now, but not much work to test. For serial communication over an
usb device one usualy has to be member of dialout.
Can you simply try to add yourself to the dialout group, logout and login
again to make it effective and check it?

prhunt · May 2, 2011, 12:38pm

Thanks Martin. This device does not seem to be a rs232-over-usb type device.

What I am going to try is creating a udev rule to set permissions for the device, and then try running both the lcdproc server daemon and client as my ordinary user.

Otherwise, it looks like I will need to work with sudo.

regards, Paul

prhunt · May 2, 2011, 11:36pm

A little development.

The lcd client, lcdproc, will run for a non-root user if it is launched as a foreground task, not as a daemon.

lcdproc, by default, will daemonize when run. I found, when I was able to invoke some stderr warnings from the LDCd server, that lcdproc was promptly disconnecting from the server. If I run it as

$ lcdproc -f
(which keeps the program running as a foreground task) then it operates as expected.

I have experimented with:

$ lcdproc &
and

$ nohup lcdproc
Anyway, I think this takes me closer to a working solution with MythTV (mythlcdserver).

Paul