Linux gpu fan control

#!/bin/bash

gpu_index_str=$(nvidia-smi --query-gpu=index --format=csv,noheader)
gpu_index=($gpu_index_str)


for index in ${!gpu_index[*]}
do
    nvidia-settings -a "[gpu:$index]/GPUFanControlState=1"
done

old_speed=-1

# fan_nums  nvidia-settings -q all | grep fan
last_fan_index=$( nvidia-settings -q all | grep fan | grep -oP "\[fan:(\d+)\]:" | grep -oP "\d+" | sort -rn | head -n 1)

echo $last_fan_index
fan_nums=$((last_fan_index+1))
echo "fan count"
echo $fan_nums

while true
do
    temperature_str=$(nvidia-smi --query-gpu=temperature.gpu --format=csv,noheader)
    temperature=($temperature_str)
    if [ $((temperature[0])) -lt 40 ]; then
        echo "temperature < 40"
        fan_speed=60
    elif [ $((temperature[0])) -lt 60 ]; then
        echo "40 < temperature < 60"
        fan_speed=90
    else
        echo "temperature > 60"
        fan_speed=100
    fi
    if [ $((old_speed)) -ne $((fan_speed)) ]; then
        for ((index=0;index<fan_nums;index++))
        do
          old_speed=$fan_speed
          # echo "fan speed flush to $fan_speed"
          
          nvidia-settings -a "[fan:$((index))]/GPUTargetFanSpeed=$((fan_speed))"
          # echo 'nvidia-settings -c:$index -a "[fan:$((index))]/GPUTargetFanSpeed=$((fan_speed))"'
        done
    fi
    sleep 300
done