LTSP needs a non-intrusive method to set a default session

[Jonathan Carter]

Currently, the default lts.conf file in Edubuntu looks like this:

"""
# see http://edubuntu.org/documentation for more information

[default]
  LDM_THEME=edubuntu
  LANG=en_US.UTF-8
  LANGUAGE=en_CA.UTF-8
  LDM_LANGUAGE=en_CA.UTF-8
  LDM_SESSION="gnome-session --session=gnome-fallback"
"""

LDM_SESSION sets the session to gnome-fallback, which is ok for a default, however, if Unity 2D is installed and a user selects it, the user will get Gnome Fallback again for subsequent logins.

LTSP needs a lts.conf tag like LDM_DEFAULT_SESSION, where a default session can be specified, but when a user has something else specified in .dmrc it would be used instead. This does not currently exist in LTSP/LDM.

[Alkis Georgopoulos (alkisg)]

I think the problem is that Unity doesn't have
  Provides: x-session-manager
and thus it breaks the update-alternatives system concept.

$ apt-cache show gnome-session | grep Provides
Provides: gnome3-session, x-session-manager

$ sudo update-alternatives --config x-session-manager
There are 2 choices for the alternative x-session-manager (providing /usr/bin/x-session-manager).

  Selection Path Προτε Status
------------------------------------------------------------
* 0 /usr/bin/gnome-session 50 auto mode
  1 /usr/bin/gnome-session 50 manual mode
  2 /usr/bin/openbox-session 40 manual mode

No Unity session there. No, gnome-session isn't enough, since Ubuntu provides a completely different shell than upstream Gnome, it should list it as a separate session.

[Sebastien Bacher (seb128)]

gnome-session is the session manager, that alternative is called "x-session-*manager*", that's not an unity bug

[Alkis Georgopoulos (alkisg)]

Fix committed in http://bazaar.launchpad.net/~ltsp-upstream/ltsp/ldm-trunk/revision/1435.
Introduced LDM_DEFAULT_SESSION, LDM_DESKTOP, and LDM_DEFAULT_DESKTOP.

[Alkis Georgopoulos (alkisg)]

Fix released in LDM 2.2.10.

It would be better to have an option to set the default desktop session in non-LTSP systems as well, but I don't think I can handle the bureaucracy that would be needed to push for that. :)