Unity depends on gdm as a desktop manager and gives empty screen in ldm

[Marc Nieper-Wißkirchen]

Under Natty, the file /etc/X11/Xsession.d/65compiz_profile-on-session reads as follows:

--------------------
# This file is sourced by Xsession(5), not executed.
# Select unity profile if we are in the default session.
# The default profile is used otherwise.

if [ "x$GDMSESSION" = "xgnome" ]; then
    COMPIZ_CONFIG_PROFILE="ubuntu"
    export COMPIZ_CONFIG_PROFILE
fi
----------------

The purpose of this script is to enable the Unity plugin in compiz in the default session (where there is no gnome-shell or -panel) so that the Unity shell is activated. There are two problems with this script:

1) The first one being that it depends on the environment variable $GDMSESSION being set while /etc/X11/Xsession runs. This leads to problems on LTSP clients where LDM instead of GDM is used so that there is no variable $GDMSESSION. (This problem could be solved in the ldm package by adding a script to /usr/share/ldm/rc.d but this wouldn't solve the problem for other desktop managers.) In Oneiric, the environment $DESKTOP_SESSION is used instead of $GDMSESSION but I am not sure whether this should be set by all desktop managers.

2) The second problem with this script is that enabling the Unity plugin depends on the session being named "gnome". This means that one cannot rename the session in /usr/share/xsessions without breaking Unity or one cannot easily install a second Unity session in this directory.

A solution would be to enable the Unity plugin while gnome-session is processing the file /usr/share/gnome-session/sessions/ubuntu.session, although I don't know how to hook a script in a gnome-session session file.

Marc

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/820328

[jhfhlkjlj (fdsuufijjejejejej-deactivatedaccount)]

Ubuntu no longer uses GDM. Is this an issue with LightDM/12.04?

[Marc Nieper-Wißkirchen (marc-nieper-wisskirchen)]

The original bug was also perceived with 11.10, where already LightDM
instead of GDM is being used. Please see my complete bug description
including details above.

2012/5/9 Chauncellor <email address hidden>

> Ubuntu no longer uses GDM. Is this an issue with LightDM/12.04?
>
> ** Changed in: compiz (Ubuntu)
> Status: New => Incomplete
>
> ** Package changed: compiz (Ubuntu) => unity (Ubuntu)
>
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> Title:
> Unity depends on gdm as a desktop manager and gives empty screen in
> ldm
>
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--
Prof. Dr. Marc Nieper-Wißkirchen

Universität Augsburg
Institut für Mathematik
Universitätsstraße 14
86159 Augsburg

Tel: [phone]
Fax: [phone]

E-Mail: <email address hidden>
Web: www.math.uni-augsburg.de/alg/mitarbeiter/mnieper/

[Sebastien Bacher (seb128)]

> This means that one cannot rename the session in /usr/share/xsessions without breaking Unity

renaming files installed by packages is not a supported option in any case...

[jhfhlkjlj (fdsuufijjejejejej-deactivatedaccount)]

If it's not supported, then I'm afraid this should be closed as wontfix. But I don't really know the official stance, so I'll just set it to 'new'