fan.sh

minSpeed=1500
maxSpeed=5500
highTemp=70
normalTemp=40

output=/sys/devices/platform/applesmc.768/fan1_output
manual=/sys/devices/platform/applesmc.768/fan1_manual

currentSpeed=$(cat $output)

[ "$1" = "" ] && echo $currentSpeed && exit 0

if [ "$1" = "auto" ]; then
        currentTemp=$(sensors | awk -F'[^0-9]*' '/Core/{sum = sum + $3; total = total + 1}END{OFMT = "%.0f"; print sum / total}')
        newSpeed=$(echo "$minSpeed + (($maxSpeed - $minSpeed) / ($highTemp - $normalTemp) * ($currentTemp - $normalTemp))" | bc | cut -d. -$
        if [ $newSpeed -eq $currentSpeed ]; then
                exit 0
        fi
else
        newSpeed=$1
fi

bash -c "echo 1 > $manual"
bash -c "echo $newSpeed > $output"
#sudo bash -c "echo 0 > $manual"

echo "$currentSpeed > $(cat $output) @ $currentTemp"