Linux Where are Ubuntu login screen video settings located?

Hi,

I want to use my DVI cable instead of my VGA cable to connect my monitor to my Ubuntu 20.04 setup which has a graphics card that outputs VGA, DVI and HDMI, however upon use of the VGA and HDMI things look fine on the login screen and I can clearly see where to type the password, however despite getting things to look ok and good with the DVI cable plugged in while actually logged into Ubuntu desktop, the login screen prior to this looks strange and is only half showing on the TV and the monitor is treated as an extension as you can see on the next post. Thanks in advance.
 
As per above
 

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Neemobeer

Windows Forum Team
Staff member
Well the login screen is called a display manager and in Ubuntu the configuration for that screen is called the greeter. There isn't going to be one-sized answer fits all since the DM and greeter can be different since multiple DMs can be used.

You can use this as a reference, but the greeter may be stored in a different location in Ubuntu or you may have a different DM in use
 
Well the login screen is called a display manager and in Ubuntu the configuration for that screen is called the greeter. There isn't going to be one-sized answer fits all since the DM and greeter can be different since multiple DMs can be used.

You can use this as a reference, but the greeter may be stored in a different location in Ubuntu or you may have a different DM in use

Thanks I'll look into it. I thought it should all be the same seeing as its such a basic function to get the image to the monitor from the graphics card. The only reason though I went back to using Ubuntu rather than Fedora was because when I wanted to use Fedora to utilise my graphics card to export video to the VGA monitor and the LCD TV via a HDMI cable that too had similar problems however it was like I couldn't display to both devices the same mirror image, it wanted me to login on the TV screen and not the PC Monitor. This made it pretty tricky when I wanted to use the PC but had to prat about turning the TV on first... It also had weird resolution issues with it.
Another strange issue I have is when I use the HDMI and VGA and DVI graphics card with the HDMI to the TV and the VGA to the Monitor, the Monitor is sooo bright I cannot see the difference between the whit lines you see for roads on Google Maps and the pale peachy background. Yet with DVI plugged in the Monitor displays things fine, thus I want to work out why I cant login properly with the DVI cable plugged in.
 

Neemobeer

Windows Forum Team
Staff member
After looking a bit, it doesn't look like this will be a problem with the DM but instead the windows manager (either X or wayland). I'm not sure what Ubuntu 20 is using. It's generally been X in the past.
 
Thanks for your help.

However, I am still no closer, I switched back tot he DVI cable to see what it was like running ubuntu original and ubuntu wayland however although the maps looked great on google, after playing with the settings to get the resolution good and to get the mirror screens function on, the computer went to crashing upon entry to the desktop after a reboot so it seems the comination of DVI plus decent resolution and mirroring was not appropriate. As it happens it refers tot he monitot as a Goldstar one, however its an LG monitor, do I need better drivers? It says the ones installed are the best (unless thats what windows says, I don't recall. Anyway I have gone back to using VGA cable, another issue that might have been useful is if there was a brightness setting in Linux ubuntu itself because then I could manually tone down the brightness. I find it weird there isn't one, when windows has one. MY brother tells me I should buy a better graphics card. I don't think its the card though.
 

Neemobeer

Windows Forum Team
Staff member
There is a brightness setting, but if it's not adjusting then you'll probably need to manually configure it in the xorg.conf
 
I have an idea, is it possible for me to remove the package for the DM and desktop environment, and reinstall with the DVI plugged up to the monitor, would it accurately detect it all then like it did with the VGA?
 
That would not affect anything. The DM doesn't configure based on detected monitors.

Any ideas on why the screen is with darker contrast allowing me to read Google Maps better in DVI connection than VGA connection? I notice the TV screen is darker using HDMI cable than the PC monitor on VGA. I wonder are brightness settings different for all three outputs? Or is it just the mechanics of the actual adaption from the graphics card that dictates contrast. If the the latter I can hopefully buy a VGA to DVI adapter and get that image I want from the VGA output.
 

Neemobeer

Windows Forum Team
Staff member
Brightness would be determined by the hardware. You'd need to adjust it on the screen itself
 
Brightness would be determined by the hardware. You'd need to adjust it on the screen itself

Well its not so much brightness, its contrast, this is why I mention the Google Maps as an example, the pictures on the screen looks ok i.e. when you see a picture of something it s find, however, on Google maps the contrast between the white lines and the peachy background is so close you cant see the roads. Maybe I should photo..
 
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