How to Control Backlight by Terminal Command

How to control backlight by terminal command

There are many possibilities. Just to name a few:

1.Bare echo

echo 8 > /sys/class/backlight/intel_backlight/brightness

For this to work, the user must be in the video group.

Look at /sys/class/backlight/intel_backlight/max_brightness to see what maximum brightness is supported.

2.The simplest to use

Install xbacklight package and then try

 xbacklight -inc 20     # increase backlight by 20%
 xbacklight -dec 30     # decrease by 30%
 xbacklight -set 80     # set to 80% of max value
 xbacklight -get        # get the current level

3.Over sophisticated

Run xrandr --verbose and look for a line with resolution like LVDS1 connected 1024x600+0+0. The name of your display (LVDS1 in this example) is needed here. Now you are ready to set brightness

xrandr --output LVDS1 --brightness 0.4

But this sets only software, not hardware brightness so you can exceed the limits (in both directons). Don't expect beautiful results but if you are brave enough to experiment a little bit then fasten your seatbelt and run

xrandr --output LVDS1 --brightness 1.7
xrandr --output LVDS1 --brightness -0.4  #yes, negative value is possible
xrandr --output LVDS1 --brightness 1

You can torture more your display with xrandr, but be ready to reboot your computer if something goes wrong. For example play with the following

xrandr --output LVDS1 --reflect x
xrandr --output LVDS1 --reflect xy
xrandr --output LVDS1 --reflect normal     # return to normal state
xrandr --output LVDS1 --rotate left
xrandr --output LVDS1 --rotate inverted
xrandr --output LVDS1 --rotate normal      # again, back to normal

How do I find the screen brightness with cmd on Windows?

You were close. Here is how you do it.

The format of powercfg is:

POWERCFG -SETDCVALUEINDEX <SCHEME_GUID> <SUBGROUP_GUID> <SETTING_GUID> value

To find out your information:

For <SCHEME_GUID>:

powercfg /q | findstr Scheme
Power Scheme GUID: a3e508ca-5ab1-4c55-bee1-9edfb71ba0a4  (HP Optimized (recommended))

For <SUBGROUP_GUID> and <SETTING_GUID>:

powercfg /q | findstr Display
  Subgroup GUID: 7516b95f-f776-4464-8c53-06167f40ca19  (Display)
    Power Setting GUID: aded5e82-b909-4619-9949-f5d31dac0bcb  (Display brightness)

Now with the GUID values and brightness in percentage - lets say 23% - like this:

powercfg -SetDcValueIndex a3e508ca-5ab1-4c55-bee1-9edfb71ba0a4 7516b95f-f776-4464-8c53-06167f40ca19 aded5e82-b909-4619-9949-f5d31dac0bcb 23

Edit: To view current britness level:

Check your current settings with the GUID: aded5e82-b909-4619-9949-f5d71dac0bcb

Just let the powercfg /q > current_settings.txt. Will save the output to current_settings.txt file and there search for the aded5e82-b909-4619-9949-f5d71dac0bcb.

For example mine:

   Power Setting GUID: aded5e82-b909-4619-9949-f5d71dac0bcb  (Display brightness)
      Minimum Possible Setting: 0x00000000
      Maximum Possible Setting: 0x00000064
      Possible Settings increment: 0x00000001
      Possible Settings units: %
    Current AC Power Setting Index: 0x00000046
    Current DC Power Setting Index: 0x00000032

The value denotes the percentage (%). The increment can be done by 1% (as you can see).

There is even MSDN page about the brightness

Linux/shell command to control screen brightness in android

Try this command too,

echo 100 > /sys/devices/platform/nov_cabc.0/leds/lcd-backlight/brightness

or

echo 100 > brightness

Change keyboard backlight with a keyboard shortcut on MacBook Pro using Automator, Shortcuts, or AppleScript

You can install Karabiner Elements online and reassign keys to different functions. There you can set whatever keys (in your case f3 &f4) to illumination down and up which will allow you to control backlit lights with function keys.

For exact procedure:

1. install Karabiner (https://karabiner-elements.pqrs.org/)
2. allow anything the app tolds you to do
3. go to the "Function Keys" tab
4. set the Target device to Apple Internal keyboard or any other keyboard you have
5. on the function keys set "vk_consumer_illumination_down" for decrease and "vk_consumer_illumination_up" for increase brightness

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