How to choose on which monitor the Lightdm greeter is displa

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How to choose on which monitor the Lightdm greeter is displa

Postby benoit.valery » 2020-03-10 07:34

Hi everybody !

I have a dual-screen configuration in a laboratory context. The primary screen (say S1) is for the experimenter, while the secondary screen (S2) is used to present information to a subject, who is placed in front of the experimenter. Debian 10 is used, and `lightdm` is the session manager. For now, the lightdm greeter is automatically displayed on S2 while in such a context, it should be displayed to the experimenter, on S1. I tried several things but none worked.

What did not work

1. Modify `lightdm-gtk-greeter.conf`
The first I tried to modify several configuration files, notably the `active-monitor` option of the `/etc/lightdm/lightdm-gtk-greeter.conf` file. Did not work. I tried both to inform this option with a either screen number (0, 1...) or a screen name (S1, S2...). Same result.
The source of this solution on https://askubuntu.com/questions/234930/ ... itor-setup

2. Execute a bash script before the greeter is displayed
One suggested solution was to execute a bash script before the greeter session is displayed. So I wrote a bash script with an xrandr command, made it executable with chmod, and passed its path to the display-setup-script option of the {i]/etc/lightdm/ligthdm.conf[/i] file, which is supposed to execute the script before the greeter is displayed. It did not work.

Installed `lightdm-gtk-greeter-settings`
I also tried to install the lightdm-gtk-greeter GUI (sudo apt-get install lightdm-gtk-greeter-settings), which allows to modify some lightdm parameters in a graphical environment, but choosing the screen where the greeter would be located was not an option.

Please, note that I'm not only looking after a lightdm solution. The solution could imply to change my session-manager. All I want is to simply control the location screen of my session greeter.

Thanks for your time !
benoit.valery
 
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Re: How to choose on which monitor the Lightdm greeter is di

Postby CwF » 2020-03-10 12:28

My lightdm login screen follows my mouse. I haven't paid attention really, but I know it will jump screens, no choosing required.
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Re: How to choose on which monitor the Lightdm greeter is di

Postby benoit.valery » 2020-03-12 07:38

Hi CwF.
Thanks for your response but I really need to control greeter location a priori, given the context.
Any more idea ?
benoit.valery
 
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Re: How to choose on which monitor the Lightdm greeter is di

Postby CwF » 2020-03-12 11:49

I'm not sure I'm clear on the problem.

The greeter will initialize on "screen0" which I assume in your config is "S2".
So first option is to physically rearrange your monitor connections and swap them. Or simply move the pointer to 'drag' the greeter to your S1 (screen1) every time.

This action is in /etc/lightdm/lightdm-gtk-greeter.conf
Code: Select all
# Login window:
#  active-monitor = Monitor to display greeter window (name or number). Use #cursor value to display greeter at monitor with cursor. Can be a semicolon separated list


So, under the [greeter] section in that file add the value active-monitor=screen1
Code: Select all
[greeter]
active-monitor=screen1

I'd assume if you have an xorg config that names the screen you could such name.
CwF
 
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Re: How to choose on which monitor the Lightdm greeter is di

Postby benoit.valery » 2020-03-12 12:03

Hi,
It's impossible to simply swap the two monitors as they use different kinds of connectors (VGA vs DVI), and are of different sizes, which is important in this experimental context.
I will try to add this option *under the [greeter] section* : in the past, I simply decommented the active-monitor option, without changing its line. Maybe that was the mistake ? I'll keep you posted.
Thanks
benoit.valery
 
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Re: How to choose on which monitor the Lightdm greeter is di

Postby CwF » 2020-03-12 12:15

benoit.valery wrote:s impossible to simply swap the two monitors as they use different kinds of connectors (VGA vs DVI)


Yes, the hardware gods have dictated VGA is always screen0! You could use adapters to swap monitors. That would be VGA>DVI for screen0, was S2 now S1. And a DVI>VGA for screen1, was S1 now S2?
...if the declaration doesn't work, good luck!
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Re: How to choose on which monitor the Lightdm greeter is di

Postby oswaldkelso » 2020-03-12 17:54

Ash init durbatulûk, ash init gimbatul,
Ash init thrakatulûk agh burzum-ishi krimpatul.
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