#!/bin/bash
pas="0.05"
maxi="1.8"
ECRAN=`xrandr | grep -i "^.* connected" | cut -f1 -d" "`
if [ -f /tmp/gamma.tmp ]; then
   g="$(cat /tmp/gamma.tmp)"
   [ 1 -eq `echo "$g < $maxi" | bc` ] && g="$(echo $g+$pas | bc)"
else
   g="$(echo 1+$pas | bc)"
fi
echo $g>/tmp/gamma.tmp
xrandr --output $ECRAN --gamma $g:$g:$g