16.04: Graphical login/desktop vanished? (coming closer)

Tom H tomh0665 at gmail.com
Tue Jul 26 13:13:49 UTC 2016

On Tue, Jul 26, 2016 at 7:34 AM, Josef Wolf <jw at raven.inka.de> wrote:

> To sum up: the core of the problem was that on a freshly installed 16.04
>   "aptitude -q -y remove network-manager"
> did remove the whole graphical desktop. (almost 600 packages)

I'm not using a "standard" DE installation at the moment so I can't
check but it may be that network-manager is a dependency of a task so
removing it triggers the removal of all the packages pulled in by that

> Strange enough, /etc/init.d/lightdm was still there and was actually
> invoked by systemd. Running it by hand did not produce any
> diagnostics. Therefore, I (erronously) assumed lightdm is still there
> but fails to start.
> That box was a clean install of 16.04, not an upgrade.
>> I pointed out that something is fishy with the OP's install.
>> 1. lightdm isn't removed
>> 2. /etc/init.d/lightdm is the wrong location, there should be a
>> systemd unit instead
> This WAS a fresh install of 16.04.
> Lightdm WAS removed.
> /etc/init.d/lightdm WAS the correct file name. Actually, it was a shell
> script with start/stop stuff etc. I know for sure, because it was by
> checking this script how I found that it tries to start
> /usr/sbin/lightdm. Only THEN I got the clue that /usr/sbin/lightdm is
> missing and started to investigate why it is missing.

"/etc/init/lightdm.conf", "/etc/init.d/lightdm", and
"/lib/systemd/system/lightdm.service" are all installed by the
"lightdm" package.

lightdm is launched by
- "/lib/systemd/system/lightdm.service" if you're using systemd
- "/etc/init/lightdm.conf" if you're using upstart
- "/etc/init.d/lightdm" if you're using sysvrc (not on Ubuntu)

A possible explanation of "/etc/init.d/lightdm" existing and being run
by systemd even though lightdm's been uninstalled is that
"/etc/init.d/lightdm" is a conffile and
"/lib/systemd/system/lightdm.service" isn't. So, if lightdm isn't
purged, "/etc/init.d/lightdm" can still exist and it'll be run by
systemd (in the absence of "/lib/systemd/system/lightdm.service") -
and presumably fail since "/usr/sbin/lightdm" won't exist.

> Any pointers to how configure NM in a scripted manner?
> Do you have a pointer? Maybe this would be a viable interface for
> quering and configuring the network stuff?

You can configure NM in two ways on Debian.

Look at the "plugins" line in the "main" section of

If it has "ifupdown" (which is there by default on Ubuntu), you can
set "managed=true in the "ifupdown" section and configure your
interface in "/etc/network/interfaces". I've only ever tested/used
this in a VM so I have no idea whether the ifupdown plugin can handle

If it has "keyfile" (which is there by default too), you can configure
a connection with a file in "/etc/NetworkManager/system-connections/",
for example on my home laptop:

# cat /etc/NetworkManager/system-connections/tom





"man nm-settings" for all options.

"tom" must have a mode of "0600" and ownership of "root:root".

My preferred NM method is the second one because it works cross-distro.

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