[mythtv-users] Mythbackend problem as daemon?

[Jarod C. Wilson]

On Tuesday, Oct 7, 2003, at 16:45 US/Pacific, Andrew Hogue wrote:

> Hi,
>
> I'm experiencing a funny little problem.
>
> When I reboot my computer and then log in and start mythfrontend, I am
> unable to watch TV.  I see a blue screen, I get audio but no video.
>
> However, I did notice that when I didn't run mythbackend as a daemon at
> startup but ran it as a process just before I started mythfrontend, I
> could watch TV perfectly fine.
>
> It seems that starting mythbackend in the startup process isn't working
> properly.
>
> Any ideas?

Yep. Red Hat by chance? And attempting to run the backend via init 
script as the user you're logging in as? Due to the way Red Hat assigns 
permissions to /dev entries, you have to launch the init script as root.

The long and short of it is that Red Hat assigns the logged in user as 
the owner of many /dev entries, including the key one here, /dev/video0 
(or what have you). The group is always root, and prior to anyone 
logging in, the owner is also root. So if you start up the backend 
before logging in (like with an init script), the permissions on 
/dev/video0 are such that the user you're trying to launch the backend 
as doesn't have permission to use /dev/video0, and things go awry.

Using the init script while logged in as that same user you're trying 
to run the backend as, the permissions are correct, so things work. To 
the best of my knowledge, you either have to change the permissions on 
/dev/video0 to world-read/write or launch the backend as root (I launch 
it as root, and have never had a problem with it).

If you're running something other than Red Hat, I'm not sure what, if 
any of this, would apply. But it sounds like it is an issue of 
permissions on /dev/video0 to me.

--Jarod

-- 
Jarod C. Wilson, RHCE

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