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I have a problem where the brightness does not save after a reboot on 14.04 LTS, but I had the same problem on 12.04 LTS (before I broke the system). Before you say this is a duplicate of a million posts, I've tried every single option that has been mentioned. I've found that xbacklght doesn't work no mater what I do with it. On my edited /etc/rc.local, however, I've set it to execute, changed the permissions so it would run without sudo and even changed the permissions of the /sys/class/backlight/acpi_video0/brightness files (and yes I've tried the actual folder as well, not just the sym link). I got it to work a few times, but only for one boot until the permission changes reset themselves. Thanks for the help in advance!

EDIT: I just remeber that I also have a folder called intel_brightness with it's own set of values that could affect how acpi_video0 works. Sorry for forgetting to add this earlier

  • Can you include your /etc/rc.local file in your question, and include some of the relevant posts that you have looked at. askubuntu.com/questions/151651/… – jmunsch Apr 23 '14 at 4:51
  • I couldn't figure out how to add my rc.local file but the value I added was echo 5 > /sys/class/backlight/acpi_video0/brightness. I've looked at every relevant post I could find. Look at the "Related" sidebar and chose one. @jmunsch – Techdroid Apr 23 '14 at 5:04
  • I should have said "can you include the contents of" instead of "can you include the file". Copy and paste the contents of /etc/rc.local it into your question by editing. This would be very helpful as well. Thanks. – jmunsch Apr 23 '14 at 5:24
  • @jmunsch I'm not at my compute now, so I can't give you the contents, but I've memorized it. (Whole bunch of commented out lines which are there by default) echo > 5 /sys/class/acpi_video0/brightness than a new line exit 0 and that's it. Hope it helps – Techdroid Apr 23 '14 at 5:36
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Try

  • Edit /etc/rc.local

    sudo gedit /etc/rc.local
    
  • Before exit 0 insert this line

    sh -c "echo  10 > /sys/class/backlight/acpi_video0/brightness"
    

This will set your screen brightness to 10/15 during startup. You can replace 10 with any integer from 0 to 15. You can save somewhere brightness value just before reboot, then you need to include a command to read the previously saved value from a file and use that value instead of 10 (in above example) to set the brightness value.

Also you can get current brightness by

cat /sys/class/backlight/acpi_video0/brightness
  • Thanks for the response, but I already added that line, which sadly never worked, leading me to ask the question here. I tried to add the '/etc/rc.local' file on my question, but I couldn't figure out how on this site. – Techdroid Apr 23 '14 at 4:30
  • if you add these lines in terminal sudo sh -c "echo 10 > /sys/class/backlight/acpi_video0/brightness" then does it work? – Back.Slash Apr 23 '14 at 4:33
  • Yes. '/etc/rc.local' works fine as well as long as you run it as root, but I can't do that with start-up, and it doesn't seem to run the way it should by running itself as root at boot – Techdroid Apr 23 '14 at 4:55

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