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Old 11-12-2012, 04:52 PM   #1
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Registered: Nov 2012
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Installing a Brightness Driver ( nvidiabl )


i installed the nvidiabl Driver from

because i cant control the display brightness on my notebook (its always at 100%).

So i opened the


file with Ubuntu Software Center and installed the package. After it was successfully installed, i tried to reduce the Brightness level with FN keys, but it doesnt work.

So i read, that i must add the line "nvidiabl" to /etc/modules.

I did this by typing sedo nano -w /etc/modules

I successfully added the line and rebooted. But i am still not able to change the screen Brightness, what do i have to do?

My Notebook is a Acer Aspire TimelineX 5830TG

Hope you can help


Old 11-15-2012, 01:24 PM   #2
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I just did this last night in Fedora 17x64 on a Lenovo T420 with nVidia drivers installed.

check your xorg.conf and add this line:
Option "RegistryDwords" "EnableBrightnessControl=1"
I found this on fedora forums

xorg.conf can be found in /etc/X11/
I recommend making a backup of the xorg.conf and add the above line between
Then restart the xserver or restart the system.

I do not have the computer from last night available at the time to print exactly where it goes but I remember it goes between the tags in xorg.conf.

Hope this helps.
Old 11-30-2012, 01:33 AM   #3
Registered: Nov 2012
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I had the same problem on an HP laptop, and it was burning my retinas. I've tried the xorg.conf solution and a host of others, to no avail. I have an AMD/ATI card, but I might be able to help:

A couple options are to download and install Redshift (
Using the following command might work:
redshift -l 0:0 -t 5800:5800 -r -b *brightness-value*&
See redshift's man page for argument descriptions, but *brightness-value* is a decimal between 0 and 1.

Anyways, because I adjust screen brightness every time I get on my computer, I wrote a Python script.

Just make sure you check and install the dependencies (see below), save the script to a file, chmod +x, and off you go.

Happy programming.

Controls screen brightness on notebooks with switchable graphics cards 
(i.e. AMD/Intel) when proprietary drivers and notebook toggle switches
are inoperative.  Though Redshift was originally designed to automatically 
change screen temperature based on lat/long and time of day, its ability  
to alter screen brightness is exploited in this script.

Edit #! above (Python path), as required for your system.

Package Dependencies:

redshift -
psutil -
python -
python-devel - install python from source gives you python-devel, or
               you can download a distro-specific package.

Written in Python 3.3
import psutil
import os

def GetRedshiftPID():  #Get Process ID (PID) for redshift
    for proc in psutil.process_iter():
        if == "redshift":
            return  #Returns redshift PID as integer
    return 0                 #Returns 0 if redshift is not running

RedshiftPID = GetRedshiftPID()

def StartRedshift():
    brightness=input("Enter desired screen brightness (0-10): ")
    brightness=brightness.rstrip()  #Strips whitespace characters
        brightness=float(brightness)  #Attempts to convert user input to a float
        if brightness not in range(0,11):
            print("Enter an integer between 1 and 10.")
            StartRedshift()  #Retry if user input is not an integer between 1 and 10
            if RedshiftPID != 0:  #If redshift is running, kill it
                os.system("kill " + str(RedshiftPID))
            if GetRedshiftPID() > 0:  #If redshift is running after first kill attempt, abort.
                print("Unable to kill Redshift. Exiting...")
            brightness=brightness/10  #Convert brightness to float for use in redshift call
            os.system("redshift -l 0:0 -t 5800:5800 -r -b " + str(brightness) + "&")  #redshift to runs in background
            print("Script Complete.  Exiting...")
        print("Enter an integer between 1 and 10.")  #If exception is caught in conversion, retry

StartRedshift()  #Begins program

Last edited by alpo85; 11-30-2012 at 01:46 AM.
Old 11-30-2012, 02:16 AM   #4
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If all this does not work you should take a look at /sys/class/backlight/acpi_video0/

there are files "actual_brightness", "max_brightness", "brightness"
cat /sys/class/backlight/acpi_video0/actual_brightness
cat /sys/class/backlight/acpi_video0/max_brightness
you can set another value for the brightness with (as root)
echo "4" > /sys/class/backlight/acpi_video0/brightness
where you have to use a useful value instead of 4, something between max_brighness and 0

Old 11-30-2012, 09:22 AM   #5
Registered: Nov 2012
Posts: 30

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Quote: should take a look at /sys/class/backlight/acpi_video0/
I've tried those, too - also to no avail.

Interesting question, though: If none of the known solutions are working on my system, how on God's green earth does Redshift work? Which values is Redshift altering?


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