Lost sound and video input - kubuntu 7.10

[Bruce Bales]

On Thursday 10 January 2008 14:40:53 Colin Pinkney wrote:
> Hi Bruce
>
> On Thursday 10 Jan 2008, Bruce Bales wrote:
> > I think the problem began about the time I tried to add my name to the
> > geneweb group.  (That didn't work, but geneweb is working for me.)
> >
> > The kmix box comes up empty.
> > alsamixer returns: function snd_ctl_open failed for default: No such
> > device but sudo alsamixer brings up the mixer.
> >
> > alsaplayer installs a null plugin and no sound, but sudo alsaplayer
> > works.
> >
> > ls -l /usr/bin/alsamixer
> > -rwxr-xr-x 1 root root 39028 2007-09-03 21:52 /usr/bin/alsamixer
> >
> > So alsamixer is executable by anyone, but not me, apparently.
>
> It looks like you somehow managed to remove yourself from the default
> secondary groups. alsamixer is executing as you, but cannot open the mixer
> device due to lack of permission when running under your account and so
> bombs out.
>
> > ls -l /dev/video0
> > crw-rw---- 1 root video 81, 0 2008-01-10 11:29 /dev/video0
> >
> > ls -l /dev/dsp
> > crw-rw---- 1 root audio 14, 3 2008-01-10 11:29 /dev/dsp
> >
> > ls -l /dev/video0
> > crw-rw---- 1 root video 81, 0 2008-01-10 11:29 /dev/video0
> >
> > Maybe there is some simple obvious solution to this, but I can't find it.
> > Anyone have any ideas?
>
> If you notice with the permissions above, only the root user (or anyone
> running sudo) and users in the groups audio and video can read and write to
> the video and audio devices. Type 'id' at the command line and it will list
> the groups you are a member of. By default the list should look something
> like this:
>
> groups=4(adm),20(dialout),24(cdrom),25(floppy),29(audio),30(dip),44(video),
>46
> (plugdev),100(users),104(scanner),112(netdev),113(lpadmin),115(powerdev),11
>8 (admin)
>
> You need to be in the audio and video groups for all these audio/video
> applications to work and if they're missing when you enter the 'id' command
> then this is your problem.
>
> To correct it at the command line you can type a series of commands like
> this (assuming 'bruce' is your actual username):
>
> sudo adduser bruce audio
> sudo adduser bruce video
> ...
>
> Alternatively you can open the System Settings in KDE and click User
> Management, switch to Administrator Mode (bottom right) and modify your
> user account to include these groups as secondary groups.
>
> NOTE: You will probably need to log out and back in again for these changes
> to take effect.
>
> HTH
>
> --
> Colin Pinkney
> http://www.cpinkney.org.uk

Yes, that did it.  Thank you very much.  I have been using linux for almost 
nine years, exclusively for seven years and I have never heard of secondary 
groups.  I'll bet that ntp hasn't been working for the same reason.

Is there any danger in adding myself to any group that looks likely 
in /etc/group ?  I see mysql, geneweb, admin, saned.  Would there be a list 
somewhere?
bruce