TIL: Changing brightntess from console

system/changing-brightness-from-console.md

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+Story: Today is my first day with Arch. Whatever problem I'm facing is clearly documented in Arch Wiki. I'm falling in love with the system. It's just another level. I feel like I don't even need to create TIL files anymore as everything is just couple of keystrokes away. I'll see how it goes.
+
+Read [this](https://wiki.archlinux.org/title/backlight) and you are done :D
+
+Here is the tl;dr part.
+
+Run `ls /sys/class/backlight/` to see which graphics card is managing your backlight. I'm assuming you get an ouput like `intel_backlight`. Then run this:
+```
+ls /sys/class/backlight/intel_backlight
+actual_brightness bl_power brightness device/
+max_brightness power/ scale subsystem/ type uevent
+```
+Read the `max_brightness` value and then set your brightness to something smaller than that value:
+```
+cat /sys/class/backlight/intel_backlight/max_brightness
+echo 100 > /sys/class/backlight/intel_backlight/brightness
+```
+Note: You should be `root` to execute the previous command. If you want to modify it without root priveleges:
+```
+/etc/udev/rules.d/backlight.rules
+
+RUN+="/bin/chgrp video /sys/class/backlight/intel_backlight/brightness"
+RUN+="/bin/chmod g+w /sys/class/backlight/intel_backlight/brightness"
+```
+and add yourself to the `video` group. 
+```
+sudo usermod -aG video $USER
+```
+
+Now you can use [`light`](https://github.com/haikarainen/light).