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I'm using 12.04 with up to date packages running on a Dell Inspiron N4030 laptop with an ATI Radeon HD 5400 graphics card. I'm using the new Catalyst 12.6 graphics driver (this version already fixed various bug with linux kernel 3.0)

The problem is when I reduce the brightness and then restart it. The brightness is not saved, even when I use a startup script:

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

When I use this script, it works initially, but then after a second the brightness changes to level 15 as if a second script is at work. Sometime when I am logged in the brightness will increase without input from me as well.

Is there is any solution?

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This is from awhile ago, but it might have some helpful information. If so, please indicate as much so your question can be marked as a duplicate. – adempewolff Aug 22 '12 at 12:10
okay I don't know how to say.. the script above is works but. in a second the brightness increase to level 15 (before in my script is 0) and when I change the brightness when already login sometimes the brightness increase too – user67036 Aug 22 '12 at 12:25
hmmm, sounds like a second script is at work. – adempewolff Aug 22 '12 at 12:30
yeah. but only in ubuntu boot screen. after going to login screen the brightness increase to 15 – user67036 Aug 22 '12 at 12:35
then it sounds like it is when lightdm loads that it is going 15. have you tried using the system-settings/brightness and lock graphical slider to adjust the brightness or have you only been using hardware keys? – adempewolff Aug 22 '12 at 12:37

If you're reducing the brightness using the buttons provided on the laptop, try this.

Open System Settings and go to Brightness & Power. Adjust the brightness and close the window. Hopefully, the settings would be saved.

Using `xbacklight`

There is an utility called xbacklight that lets you set the brightness of your screen.

Installing: sudo apt-get install xbacklight

Increasing/Decreasing the brightness: xbacklight -set X% where X is between 0 to 100.

You can add this in "Startup Applications" or add this command to /etc/rc.local.

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thanks for answer, but when I'm trying login again the brightness is back to 15 – user67036 Aug 22 '12 at 12:53

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