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I have recently installed 12.04 on ASUS-K53SV-V300. I can change the brightness on start-up with:

echo 0 > /sys/class/backlight/acpi_video0/brightness >> /etc/rc.local

or manually by Fn key.

But, whenever Ubuntu dim my screen brightness to save power or wake-up from suspend or inactive for 20-30 seconds, brightness reset to high (my problem get much more when on battery).

How can I disable screen brightness service to prevent it from changing my brightness? What service work on screen brightness? If I disable this service, can I manually set brightness by command?

find a replacement to work on brightness instead of default power manager.

share|improve this question… – Raja Aug 28 '12 at 2:09

You can turn off brightness adjustments to save power in System Settings->Brightness and Lock.

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In case you don't want your screen to turn off or dim at all, I recommend the tool Caffeine.

sudo apt-add-repository ppa:caffeine-developers/ppa
sudo apt-get update && sudo apt-get install caffeine

If you turn on Caffeine, it will prevent your screen from dimming and switching of. That tool always worked for me.

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I have read the core codes of the tool caffeine which written by Python mentioned above and I found the command 'xset -dmps;xset s off' seems useful.

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