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lightum - MacBook automatic light sensor daemon

© 2011-2012 Pau Oliva Fora - pof[at]eslack(.)org

Lightum is a daemon to control the keyboard brightness and screen backlight on MacBook based laptops.

By default it will run in "auto" mode, this means it will read data from the ambient light sensor (located on the iSight camera) and automatically:

  • light up or dim the keyboard brightness
  • light up or dim the the video backlight

It will also dim the keyboard brightness and screen backlight when the computer is not used for a configurable amount of seconds.

If you choose to run it in "manual" mode, it will not query the ambient light sensor, but instead it will use the brightness and backlight values you set manually using the function keys.


When first launched lightum will create a configuration file inside the user's home directory with the default configuration values:


When launched without parameters, lightum will read the configuration from this config file, but the configuration values can be overwritten via the command line:

Usage:  lightum [OPTION]...
 -m 4..255 : maximum brightness value in auto mode (default=255)
 -n 0..3   : minimum brightness value in auto mode (default=0)
 -M 7..15  : maximum backlight value in auto mode (default=15)
 -N 1..6   : minimum backlight value in auto mode (default=1)
 -p num    : number of milliseconds between light sensor polls (default=300)
 -i num    : power off keyboard light on session idle seconds (0 to disable)
 -I num    : turn down screen backlight on session idle seconds (0 to disable)
 -w num    : 1 manage brightness, 2 manage backlight, 3 both (default:3)
 -x        : manual mode (will honor the brightness value set with Fn keys)
 -l        : fully dim the screen backlight when session is idle
 -u        : do not ignore brightness changes happening outside lightum
 -U        : ignore session information from ConsoleKit
 -s        : power off keyboard light when screen saver is active
 -f        : run in foreground (do not daemonize)
 -v        : verbose mode, useful for debugging with -f and -d
 -d num    : debug mode: 1 brightness, 2 backlight, 3 both

Ubuntu packages

Official Ubuntu packages are available in poliva/lightum-mba ppa:

 sudo add-apt-repository ppa:poliva/lightum-mba
 sudo apt-get update
 sudo apt-get install lightum

Compiling from source

(Tested on Ubuntu 13.04)

  1. Install the build-essential package: sudo apt-get install build-essential
  2. Clone the repository by running git clone and cd into the project's directory.
  3. Install the dependencies sudo apt-get install libxss-dev libdbus-glib-1-dev
  4. Run make
  5. Run sudo make install

Indicator applet

An indicator applet is also available to control lightum from your desktop panel.

Enjoy! :)


MacBook automatic light sensor daemon







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