[conspire] launching LXDE

[Rick Moen]

Quoting Paul Zander (paulz at ieee.org):

> So how to run LXDE not gnome.
>    /usr/sbin/lightdm
> 
> That is obviously not gdm, and is also what a different computer has.
> That machine runs LXDE.

(Quick answer is in the closing paragraphs, below.)

Lightdm is a display manager from Canonical.  As the name suggests, it's
more lightweight than gdm is.

As a review, if you are running a graphical login screen that screen is
provided by a special type of X11 client (application) called a display
manager.  The old-school, basic, plain display manager is xdm.  KDE,
GNOME, Enlightenment, and a whole lot of other DE and window manager
projects have created alternative display managers, some plain and
others fancy.  LXDE itself has one:  Predictably, it's calle lxdm.

Most display managers fancier than xdm have controls to select what DE
or window manager to use for the current login, and sometimes to change
what will be the default selection for the future.  Lightdm is like
that, I (very) vaguely recall.

(Bear in mind, I'm trying to answer your question without installing and
running Lightdm.  I'm an xdm guy.)

https://wiki.ubuntu.com/LightDM says some useful things about asserting
control over Lightdm.  I gather that Lightdm picks the DE to start by 
specifying a 'session' to run.  That's another X11 concept, the 'X
session manager':  The X session manager is another specialised X11 app
(client) whose job it is to make sure a bunch of DE service processes
get launched at login time.  (You may notice that most DEs default to
restarting at next login whatever apps you had running at the end of
your prior login session.  That's the X session manager that does that.)

Looks like you do:

lightdm-set-defaults --session [session name]

What's the session name to specify for LXDE?  Not sure, maybe 'lxde'?
There is also an Lightdm conffile, something like
/etc/x11/lightdm/lightdm.conf , that may be worth looking at.


> Other source say to edit /etc/X11/default-display-manager.

Random Internet advice is risky.  ;-> 

That file, among many others, is best managed using your distro tools.
In Debian/Ubuntu-family distros, the right way to select among your
available X Display Managers is like so:

update-alternatives --configure x-display-manager

You'll find many other useful update-* administrative tools usable by
the root user.   They will manage your system in an orderly fashion. 



The above discourse about Lightdm assumes that you have some reason to
want to continue to run Lightdm, which may in your case not be true.  If
you'd rather not wrestle with Lightdm, then do:

apt-get remove lightdm notification-daemon
(This gets rid of Lightdm and other related crud, notifcation-daemon
being a GNOME thing implementing the Desktop Notificaitons
Specification, if you care.)

apt-get install lxdm
That's why I personally would do, and should Just Work.

You can select among available X window managers by doing:

update-alternatives --configure x-window-manager