sct - set color temperature of screen
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Failed to load latest commit information. Fix memleak Nov 21, 2015
sct.c Fix crash when DISPLAY env variable is set to an invalid value May 31, 2016


Sct (set color temperature) is a UNIX tool which allows you to set the color temperature of your screen. It is simpler than Redshift and f.lux.

Original code was published by Ted Unangst:

Minor modifications were made in order to get sct to:

  • compile on Ubuntu 14.04
  • iterate over all screens of the default display and change the color temperature
  • free the Display structure
  • fix memleaks
  • clean up code
  • return EXIT_SUCCESS


Compile the code using the following command:

cc -std=c99 -O2 -I /usr/X11R6/include -o sct sct.c -L /usr/X11R6/lib -lm -lX11 -lXrandr

Execute sct using the following command:

./sct 3700

The first parameter (3700 above) denotes the color temperature and can be between 1000 and 10000. If sct is called without parameters, sct sets the color temperature to 6500.