Auto fan control script for Raspberry Pi

fan_ctrl.sh

#!/bin/bash

temp_on=50000
temp_off=45000
#connected to GPIO18
fan_gpio=18

temp=`cat /sys/class/thermal/thermal_zone0/temp`

# init GPIO
gpio -g mode $fan_gpio out

# get status gpio
fan_status=`gpio -g read $fan_gpio`

if [ $fan_status = 0 ] && [ $temp -ge $temp_on ]; then
    # fan start
    gpio -g write $fan_gpio 1
fi

if [ $fan_status = 1 ] && [ $temp -le $temp_off ]; then
    # fan stop
    gpio -g write $fan_gpio 0
fi

exit 0