As you may know, screen brightness drains battery, that's why it is considered a big problem for laptops (at least for me).

I can change the screen brightness but every time ubuntu boots up I will have to change it again.

Luckily, you can write a script that does that for you. However, when the laptop is plugged in I do want the maximum brightness; which means I will have to do that by myself every time I plug in the laptop.

Is there a script that detect if the laptop is charging or not and sets the brightness level accordingly?


On my laptop I can check the contents of the file /sys/class/power_supply/C1BC/online: if the laptop is plugged in this file contains 1, otherwise it contains 0.

For example,

if [ "1" = "`cat /sys/class/power_supply/C1BC/online`" ]; then
  echo "Laptop is charging/plugged"
  echo "Laptop is discharging/unplugged"

Note. As confirmed by the OP, the C1BC part is system dependent.

  • 1
    Thanks, it worked. Mine was ACAD though. – Mhmd Nov 13 '14 at 19:46

Try this

To adjust brightness in xubuntu or ubuntu Open a terminal window, and execute this command to edit /etc/rc.local:

sudo nano /etc/rc.local

Add this before the last line “exit 0″:

echo xx > /sys/class/backlight/acpi_video0/brightness

Where number xx is the value of your screen brightness of your choice.

The maximum value for brightness can be found with:

cat /sys/class/backlight/acpi_video0/max_brightness

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