[LightDM] Setting default X session

Didier Roche didrocks at ubuntu.com
Thu Aug 11 23:27:00 PDT 2011

Le 11/08/2011 17:48, Robert Ancell a écrit :
> On 20 July 2011 12:52, Сергей<shnatsel at gmail.com>  wrote:
>> In the version from recent Oneiric dailies I've worked it around with
>> setting session=<session name>  under [seat-0] in /etc/lightdm/lightdm.conf,
>> but there are some distribution and dpkg-related issues that are not really
>> lightdm's fault (https://bugs.launchpad.net/bugs/799754), and I'm afraid I
>> can't edit /etc/lightdm/lightdm.conf at all until that bug is fixed (or use
>> very ugly hacks - GRRRR!). Ubuntu seems to use undocumented features of
>> greeter (?!) or something like that, without tweaking lightdm.conf they have
>> the session name passed to the wrapper script as a parameter but I have no
>> idea where do they set it... Oh well. I'm afraid I can only ask Ubuntu
>> engineers about it now.
> If you're using a LightDM 0.9.0+ then the correct config is:
> [SeatDefaults]
> user-session=<session name>
> In the current Ubuntu package the default is "gnome", but this is a
> temporary fix.  Didier Roche (cc'd) is working on the correct solution
> so that derivatives can work more easily (the installer (casper) will
> write lightdm.conf, it will be written when first installed, etc).

The default is now "ubuntu" in the Ubuntu package ;)
There is a tool in trunk (since the last 3 days) that we backported in 
Oneiric that I wrote called lightdm-set-defaults (you can find it in 
/usr/lib/lightdm/), which enables you to set the greeter and the default 
session you desire.

Package should in their postinst call this one to set themselves as 
default (using the --keep-old options) and remove them on 
install/removal. For instance:
to set the default session to "ubuntu" for the ubuntu desktop case.
for the greeter.

So basically, installing them will set the first installed one (we don't 
expect having multiple greeters in a CD spin for instance) as the 
default. Then, casper has now a fix for just adding the autologin part 
without hammering those things:

Please note that this is very similar to the patches I made for gdm back 
in the lucid days (10.04) which seems to have fit the numerous flavors 
and derivatives we have.


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