I have an Acer Inspire 5733-6838 Notebook with an Intel HD chip. I can adjust the screen brightness both in KDE and using the keys on the keyboard to adjust then slider. However, the screen itself is stuck on full brightness no matter what I do. How can I fix this? Using the latest Manjaro x64 build.

Please check which devices are present in /sys/class/backlight - in particular, if more than one is present please try echoing certain values into the "brightness" file there so see if that changes the screen brightness. You'll need to use a root terminal to do that however.

Please ensure you check the max_brightness file contents before doing this.

I suspect one or more of these will have no effect - which is why KDE Power Management is not having any visible effect on screen brightness.

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[xplorer4x4@xplorer4x4-hcm ~]$ ls -al /sys/class/backlight
total 0
drwxr-xr-x  2 root root 0 15.07.2014 14:40 ./
drwxr-xr-x 42 root root 0 15.07.2014 14:40 ../
lrwxrwxrwx  1 root root 0 15.07.2014 14:40 acpi_video0 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0/
lrwxrwxrwx  1 root root 0 15.07.2014 14:40 intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight/

This is the contents of the directorey mentioned. No brightness file is present. There is the backlighting but thats it. So not sure where to go from here,

You will find the 'brightness' file within each of those subdirectories. That output looks fairly normal to me - will be interesting to see if one of those works while the other doesn't...

bcooksley wrote:You will find the 'brightness' file within each of those subdirectories. That output looks fairly normal to me - will be interesting to see if one of those works while the other doesn't...

Sorry didnt read closely.
I tried using the brightness file in the Intel dir, and sure enough, it works.

Trying to make a bash/kdialog script that will prompt me when executed and inject a rightness value from the dialog. The script work for writing to a test.txt file in the home dir. But gives me an error when writting to the brightness file.
line 2: /sys/class/backlight/intel_backlight/brightness: Permission denied

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#/bin/sh
kdialog --title "Input dialog" --inputbox "Brightness Level" "value" sudo echo > /sys/class/backlight/intel_backlight/brightness

You need to be root in order to write to those files i'm afraid, and as "echo" is a shell builtin, you need to run the command as follows instead:

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kdialog --title "Input dialog" --inputbox "Brightness Level" "value" sudo sh -c "echo > /sys/class/backlight/intel_backlight/brightness"

[xplorer4x4@xplorer4x4-hcm ~]$ brightness.sh
kdialog: Unknown option 'c'.
kdialog: Use --help to get a list of available command line options.

You may need to use an argument separator (--) or wrap the whole command in another script/quotes.