If your laptop or netbook having same scenario as mine, here's how to fix it:
- Edit the 'rc.local' file. In terminal:
- Add the code below into the file, before the line exit 0:
gksu gedit /etc/rc.local
echo 7 > /sys/class/backlight/acpi_video0/brightness
The number 7 represents the display brightness level you want. Save and close this file.
The range of brightness level is different on different computers. You can check the maximum brightness level for your computer via this path: /sys/class/backlight/acpi_video0/max_brightness. For my HP mini 210, the max brightness is 10. So this means the range of brightness level for my netbook is from 0 to 10.