Logitech Webcam Pro 9000 only works when motion is run as root

Question

So I have a Logitech Webcam Pro 9000 under 10.04 and I am trying to get it to work with Motion.

Here is the lsbusb output:

Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 008: ID 046d:0809 Logitech, Inc. 
Bus 001 Device 005: ID 15a9:0004  
Bus 001 Device 004: ID 058f:6362 Alcor Micro Corp. Hi-Speed 21-in-1 Flash Card Reader/Writer (Internal/External)
Bus 001 Device 002: ID 1058:0910 Western Digital Technologies, Inc. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

When I run Motion as user "motion" it doesn't work and I keep getting a Failed to open video device /dev/video0 error. However, when I run it as root, there is no problem and everything works fine.

I have a laptop running the same setup for motion and everything seems to work fine e.g. all the permissions on the files and the device are the same.

Any thoughts?

Answer 1

Figured it out.

Looks like the motion user wasn't part of the video group.

e.g.

$ id motion 
uid=1001(motion) gid=1001(motion) groups=1001(motion)

So I did a:

sudo usermod -a -G video motion

and it worked. This is how it looks now:

$ id motion
uid=1001(motion) gid=1001(motion) groups=1001(motion),44(video)

I also noted that the motion user has a user uid and not a system uid. I think this may be because I added the user manually after an update instead of using the default user created by installing Motion.