How can I run kscreen-doctor on startup before login (to disable my external TV screen from showing login dialog)?

Help
,
1

Hi all!

I am running KDE 6.2.4 on Fedora 41, already tried asking over in the Fedora forum, but unfortunately did not get any response, so I am hoping you guys can help me out :slight_smile:

In addition to my monitor, I have a TV screen that I don’t use very often. I would like to only enable it as a display on demand via a script which also launches other gaming stuff on that TV. From disabled state, this works fine with “kscreen-doctor output.HDMI-A-1.enable”.

However, when I shutdown the system, the screen is always enabled on next boot and displays the login screen.

Is there a way to run something like “kscreen-doctor output.HDMI-A-1.disable” on boot, or before the login screen is setup? Or any other way to disable the output and enable it later with a command?

I have tried following sddm documentation and placing a file in /etc/sddm.conf.d/ which contains
[X11]
DisplayCommand=kscreen-doctor output.HDMI-A-1.disable

…but this does not seem to get triggered. Replacing the command with “/bin/touch /tmp/testfile” does nothing so I guess this never gets executed.

Any ideas on how to run stuff on boot/before login?

Thanks and gave a great day!

2

this sounds like it may require a kernel level intervention.

blacklist the monitor on boot, but then some how enable it after on demand.

don’t even now if this is possible, just spitballing.

3

Hi, great idea! I tried to disable the output on boot by adding this to the boot command line:
video=HDMI-1:d

…but then the TV stays dead and I cannot find a way to reactivate it at all :frowning:

4

ur half way there… farther than i would have got. :upside_down_face:

5

SDDM doesn’t run on Xorg on Fedora.

To do what you want, you don’t have to run any commands or the like. There’s a button in the system settings page for SDDM to synchronize settings to it - that includes (the Wayland sessions) display settings. In your session, just create whatever display setup you want SDDM to have, and then synchronize the settings to it.

2 Likes
6

Amazing, never noticed that button, but that did the trick, thank you for your help! Finally I can login via the correct screen.

No matter where I looked, I was not able to find a way to configure this via CLI. Would you by chance have any idea where the relevant config could be located, and point me in the right direction?

7

The config for display settings is in ~/.config/kwinoutputconfig.json of each user. I don’t know where the SDDM user’s data is stored though.