where are the device video0 ;...

Amadeus W. M. amadeus84 at cablespeed.com
Thu Dec 29 19:49:54 UTC 2005

On Thu, 29 Dec 2005 19:36:43 +0100, Francois Massonneau wrote:

> On Thursday 29 December 2005 19:17, Amadeus W. M. wrote:
>> > I'm trying to install a webcam, and from what I read, I have to check a
>> > device named "video0", or ("video" which is a simple link to video0).
>> > But inside my /dev directory, I have no video? file(s) at all.
>> > How do I do to create one ? I run Fedora Core 4.
>> > Thank you. Francois
>> > --
>> mknod /dev/video0 c 81 0
> No, that's not the right way imho. Each time I reboot the machine, that 
> device disapears and I have to recreate it.
> I read lots of messages about that, and the latest I've found says to create 
> a  /etc/udev/rules.d/06-dvb.rules file and to add the following lines:
> KERNEL="dvb*", PROGRAM="/etc/udev/scripts/dvb.sh %k", NAME="%c"
> SYSFS{vendor}="0x109e", PROGRAM="/etc/udev/scripts/dvb.sh %k", NAME="video0" 
> As the card is a Pinnacle Dv500, I changed the 0x109e to 0x104c, as it seems 
> it's the vendor id of my card, but again, it's doesn't work ;-(
> Francois
> --

That's because in the 2.6 kernel the udev system creates nodes in /dev
dynamically, only for devices that are actually present.

I don't pretend to understand the internals of udev, but rpm -qil udev
showed a bunch of man pages which might shed some light. Don't know if
you've seen those.

For a hardware device to be recognized, the system must have the right
driver. If you don't have the right driver, the system won't see the
camera, hence won't create the /dev/video0 link. 

You do know that any usb camera needs a specific driver, don't you? A
while back when I was messing with my own webcam, I did a search on
"webcam +linux" or something similar, and I found a page listing the
supported cameras and the status of the drivers.

Sorry I can't help more than just pointing out to some things that I'd
look into if I had to.

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