[rhelv6-list] Gnome - KDE Desktop switching in RHEL6

[Horst Severini]

Hi Hugh and Gianluca,

> gdm uses the *.desktop files in /usr/share/xsessions to determine
> which choices to make available at login time.
> /usr/share/xsessions/kdm.desktop is owned by the kdebase-workspace rpm
> which is part of the kde-desktop yum group.
>
> If the file is there, I'd make sure the permissions are correct on it.

Hmm, that file exists and has the same ownership and permissions as 
gnome.desktop, so I don't think that's the problem.

But after I created /etc/sysconfig/desktop with

DISPLAYMANAGER=KDE

and restart X, then it did come up with KDM instead of GDM, 
and there I do have the options to switch back and forward 
between KDE and Gnome, so that's great!

I still don't understand why I don't see the option to switch in GDM, 
but hey, at least I have a working setup now!

Thanks a lot,

       Horst

Gianluca Cecchi <gianluca.cecchi at gmail.com> wrote:

> On Sat, Feb 8, 2014 at 12:06 AM, Horst Severini wrote:
> > Hi all,
> >
> > we are working on upgrading our desktop cluster from RHEL5 to RHEL6, and we
> > think we have a workable solution that involves bringing up the new machines
> > with ROCKS 6.1 and the RHEL 6.5 ISO, and then doing some post-config via
> > scripts, but when we do that, we only have Gnome available at the login
> > screen, and we can't figure out how to make KDE available as well.
> >
> > We have all the KDE RPMs installed (that I know of), via
> >
> > yum groupinstall "KDE (K Desktop Environment)"
> >
> > and I have compared the list of installed RPMs with one RHEL6 test install
> > we did manually, and I can't figure out what's missing, since everything
> > that looks like it's even remotely related to KDE and desktop switching is
> > already installed, so I don't know why the ROCKS installed machines don't
> > show the desktop switcher box at the bottom of the login screen.
> >
> > I tried googling around, but haven't quite found the right page yet.
> > What are we missing?
>
>
> What worked for me on a CentOS 6.5 install where I had only Gnome and
> init level was 5 by default:
>
> sudo yum groupinstall "KDE Desktop"
>
> verify you have kdm executable (in practice the kdm rpm package)
> vi /etc/sysconfig/desktop (is not present by default)
>
> put into it the single line
> DISPLAYMANAGER=KDE
>
> $ sudo init 3
> $ sudo init 5
>
> and I get kde diplay manager.
>
> take into account that display manager in 6.5 is managed by upstart
> init script prefdm.conf in /etc/init directory
>
> and at the end it runs
> exec /etc/X11/prefdm -nodaemon
>
> and prefdm contains:
>
> if [ -f /etc/sysconfig/desktop ]; then
>         . /etc/sysconfig/desktop
>         if [ "$DISPLAYMANAGER" = GNOME ]; then
>                 preferred=/usr/sbin/gdm
>                 quit_arg="--retain-splash"
>         elif [ "$DISPLAYMANAGER" = KDE ]; then
>                 preferred=/usr/bin/kdm
> ....
>
> Otherwise some lines below it contains:
> # Fallbacks, in order
> exec gdm "$@" >/dev/null 2>&1 </dev/null
> exec kdm "$@" >/dev/null 2>&1 </dev/null
>
> so you can comment out the one starting with gdm and it will start kdm
> if it finds it...
>
> If you like a display manager not managed by prefdm you have to create
> a prefdm.override in /etc/init and put there your display manager
> commands/options
>
> HIH,
> Gianluca
>
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