Free Software Alternative to f.lux

Try redshift. It's in the Trisquel repository.

For active LCD, you can set the brightness manually with “xbacklight -steps 1 -set BRIGHTNESS” I use “light BRIGHTNESS”. I have the following lines in my .bashrc:

function light () {
if [ $# == 1 ]; then
xbacklight -steps 1 -set $1
elif [ $# == 0 ]; then
xbacklight
fi
}

The scale goes from 0 to 100. Typing “light” in the command line prompt will give you the current brightness.

I believe this chunk of code is not copyrightable due to triviality, but for the avoidance of doubt: I hereby place it in the public domain under the terms of the Creative Commons CC0 public domain dedication. Note: I'm not a supporter of public domain or permissive licenses for non-trivial works.