2011 8,3 MacBook Pro running 64bit 11.10.

The screen brightness keys seem to actually do things, but nothing actually changes with regard to actual laptop screen brightness. (See this video. Ubuntu can sense when the buttons are pressed, but nothing actually happens with screen brightness. I know you wouldn't be able to see it if it did work, but it doesn't.)

Is this a known issue? How can I adjust the screen brightness on my MacBook Pro?

I know I can do something like this in the AMD/ATI FGLRX configuration software, but it actually just adjusts the output picture, not the physical laptop's screen brightness. What can I do?

  • 1
    I opened this thread on ubuntuforums, i find it another useful place to get answers: ubuntuforums.org/showthread.php?p=11566082 The reason is i wanted the world to know i also have this problem, and that modifying the brightness file doesn't work for me also. Feel free to remove this "answer". – user39392 Dec 26 '11 at 19:43
  • The reason you get "permission denied" is due to a problem in the way he wrote the script above. Try echo 10 | sudo tee /sys/class/backlight/acpi_video0/brightness. That'll do what he's intending, but it doesn't update things for me at least. – Naftuli Kay Dec 26 '11 at 20:31
  • Do you still have this problem? I'm running 12.04 on a Macbook Pro 8-2 and I can change the screen brightness using the "default" brightness media keys after a standard installation. I can change the brightness setting also by changing the value in /sys/class/backlight/gmx_backlight/brightness. – user24668 May 12 '12 at 7:04

Are you using ubuntu on mac? If yes then you can change your screen brightness using the following command:

echo 4 | sudo tee /sys/class/backlight/acpi_video0/brightness

Value range: 1 to 10 [1 lowest, 10 highest]

Also you can set the brightness at start-up. Append the line in /etc/rc.local before exit 0

  • I don't think that does anything, actually. Here's a tree of the /sys/class/backlight/acpi_video0/ directory, if that helps: pastebin.com/gmgYmPJR – Naftuli Kay Dec 26 '11 at 19:14
  • It actually does write to the files, but nothing really changes. Could there be something I need to do in Xorg? – Naftuli Kay Dec 26 '11 at 19:23
  • "No such file or directory" – Cerin Mar 11 '12 at 18:19

I have a white MacBook running Ubuntu and the brightness keys work fine; however, it does seem to be an issue with the MacBook Pro (I don't have one handy to test on). But I did find this in my search. It looks like a script that you can bind to a key event. The tutorial covers KDE, but binding a script to a key in Gnome is relatively simple as well, if I recall correctly. Does this properly address your problem?

  • Unfortunately, I don't seem to have anything at all under /sys/devices/virtual/backlight. Is there a module I need? Again it's an 8,3 MBP and I'm running 11.10. – Naftuli Kay Jan 31 '12 at 16:01
  • I'm having this issue too, with a white MacBook. It worked some time ago, I just notice it doesn't work anymore. It's definitely not a MBP issue. Also happens with MB White. – verpfeilt Dec 21 '12 at 19:35

Apparently, you need to boot to EFI, not to emulated BIOS, as is what happens with rEFIt.

  • Are you booting Ubuntu using UEFI now? Or have you simply given up on finding a solution :) – user24668 May 12 '12 at 7:05
  • Yes, if you boot using OSX's native boot screen rather than rEFIt, it seems to work. – Naftuli Kay May 13 '12 at 15:40
  • What do you mean by "it seems"... :P – user24668 May 13 '12 at 15:44
  • It works. Period. – Naftuli Kay May 13 '12 at 16:16
  • E.g. Does Ubuntu see your integrated graphics? If it boots using BIOS emulation, you'll only be able to use discrete graphics. That's the problem that I'm having. The battery life is therefore short and my MBP is generally hot. – user24668 May 13 '12 at 16:51

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