brightnessctrl
==============

Introduction:
1. Brightness control with 256 levels of brightness and OSD notification for unity.
2. You have to make the command setpci sudoable without password. See how - http://askubuntu.com/questions/159007/specific-sudo-commands-without-password
3. Works with intel PSB driver but can be edited to work with others.
4. The OSD notification is handled by a separate script and is designed to look good in Unity's notifyOSD.

Output of brightnessctrl -h:
#Begin output##################
Usage: 
    brightnessctrl [-h/--help] [-o/--osd] brightness-option

Notes:
   1. Brightness is an integer between 0 and 255 (inclusive).
   2. Do not use more than one brightness option at once.
   3. Be careful not to set brightness to 0 - not that this is fatal.

Options:
  -h, --help       show this help message and exit  
  -o, --osd        Display OSD Notification  
  -g, --get        Print current brightness  
  -s S, --set=S    Set brightness to S  
  -p P, --plus=P   Increase brightness by P  
  -m M, --minus=M  Reduce brightness by M
#End output####################

How it works:

1. It uses the setpci command to set brightness and this should with all drivers.
2. Because setpci needs sudo access, you have to make it sudoable without password prompt.
3. To get the current brightness (-g) and to use that to increase and decrease brightness (-p/-m) it looks into the file /sys/class/backlight/psb_intel_backlight/actual_brightness.
4. The maximum brightness (255) corresponds to 398310 in that file and the minimum (0) to 0 (linear scaling). Intermediate levels of brightness (say between 0 and 398310/255) don't work.

How to modify this script for other drivers:

1. Look into the directory /sys/class/backlight/ and find the appropriate actual_brightness file.
2. Set brightness to maximum (by other methods) and see the contents of this file with cat actual_brightness.
3. Change the values of actual_brightness_file and maximum_brightness_in_file in brightnessctrl.
4. /sys/class/backlight/acpi_video0/ has only about 10 levels of brightness, so this work with that.
5. It may be the case that there is no driver which shows more than 256 levels of brightness.