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I have installed xbacklight and am getting 'No outputs have backlight property' on executing

xbacklight -set 50 OR

xbacklight +10

My system directory: /sys/class/backlight is empty

I have seen some solutions for the same but am unable to change brightness from terminal.

This is the result of xrandr -q --verbose

Screen 0: minimum 16 x 16, current 1920 x 975, maximum 32767 x 32767
XWAYLAND0 connected 1920x975+0+0 (0x51a) normal (normal left inverted right x axis y axis) 0mm x 0mm

Identifier: 0x21
Timestamp:  17063948
Subpixel:   unknown
Gamma:      1.1:1.1:1.1
Brightness: 26.
Clones:    
CRTC:       0
CRTCs:      0
Transform:  1.000000 0.000000 0.000000
            0.000000 1.000000 0.000000
            0.000000 0.000000 1.000000
           filter: 
non-desktop: 0 
    supported: 0, 1



1920x975 (0x51a) 155.250MHz -HSync +VSync *current +preferred
        h: width  1920 start 2040 end 2240 total 2560 skew    0 clock  60.64KHz
        v: height  975 start  978 end  988 total 1012           clock  59.93Hz

please help me

sancho.s ReinstateMonicaCellio
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Jay B
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1 Answers1

2

Use

xrandr -q

to learn the name of your display. Then

xrandr --output <display name> --brightness <level>

Note: for a finer control (albeit via GUI, I am not sure it has a CLI), you can use brighness-controller

sudo add-apt-repository ppa:apandada1/brightness-controller
sudo apt-get update
sudo apt-get install brightness-controller

Related:

  1. Ubuntu 20.04 brightness adjust not working
sancho.s ReinstateMonicaCellio
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  • Using xrandr -q, I have got the result, Screen 0: minimum 16 x 16, current 1920 x 975, maximum 32767 x 32767 XWAYLAND0 connected 1920x975+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 1920x975 59.93*+ – Jay B Feb 22 '21 at 13:11
  • Using xrandr -q, I have got the result, --- starts here --- Screen 0: minimum 16 x 16, current 1920 x 975, maximum 32767 x 32767 XWAYLAND0 connected 1920x975+0+0 (normal left inverted right x axis y axis) 0mm x 0mm 1920x975 59.93*+ --- ends here ---. I have used the command ---starts here --- xrandr --output XWAYLAND0 --brightness 100 --- ends here ---. I have taken XWAYLAND0 as the display name and i don't see any difference in brightness, terminal goes to new line without any terminal output – Jay B Feb 22 '21 at 13:21
  • Hi sancho.s, I can't see anything like primary that on executing xrand -q – Jay B Feb 22 '21 at 13:24
  • Dear sanchos, Added the reslt for xrand -q --verbose – Jay B Feb 22 '21 at 13:44
  • I have installed the brightness controller but it seems changing the colour temperature of screen. I hope i could alter the screen brightness as like it happens in windows. When i dual booted ubuntu 18.04 i was able to change brightness from keyboard switches only. This could be the because i am using ubuntu in VM now – Jay B Feb 22 '21 at 13:48
  • @JayB - XWAYLAND0 is the name I was refering to. Please try with that and give feedback. – sancho.s ReinstateMonicaCellio Feb 22 '21 at 15:00
  • Hi sanchos! I have tried with the XWAYLAND0 as the name right then but the terminal goes to new command line with no change in backlight brightness or any other output in any way. I run it now, it's the same. After reading some answers, i think there is a lot to do with graphics driver brand and other specs of device – Jay B Feb 24 '21 at 17:34