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I'm on a Dell Latitude E6320, and the screen doesn't get very dim. It's way too bright even when it's dimmed as far as Ubuntu will let it. How do I dim it more?

For example, when you have this problem on a windows system, you can install a program like Dimmer (http://www.mylittlehost.com/dimmer.aspx) that overlays a black over your whole display (and you can configure the opacity, allowing you to dim the screen beyond the normal max). Is there any way to deal with a too-bright screen in linux?"

Thank you!

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up vote 3 down vote accepted

The interface /sys/class/backlight has this. I.e.

echo 4000 > /sys/class/backlight/intel_backlight/brightness 

Other interesting values are:

cat /sys/class/backlight/intel_backlight/max_brightness
cat /sys/class/backlight/intel_backlight/actual_brightness

Please note, pr. default, these are writeable by root only.

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You can use setpci to change these values as a normal user. The syntax is more cryptic though. For my system this is setpci -s 00:02.0 F4.B=XX where XX is a hex value between 00 and ff. The device (after the -s) can be found out with 'ls -l /sys/class/backlight/intel_backlight' where I see devices/pci0000:00/0000:00:02.0 in the device path. – Christian Jun 25 '12 at 7:39
Oh and be careful in either case with 0 as display brightness. I have a Pixel Qi display and I will see something with the backlight switched off completely (and I searched long for a way to accomplish this) but you most likely won't see much so have a reverting line in your bash history where you can find it blindly. – Christian Jun 25 '12 at 7:44

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