Log Raspberry Pi temperature to text file

checktemp.sh

#!/bin/bash
cpuTemp0=$(cat /sys/class/thermal/thermal_zone0/temp)
cpuTemp1=$(($cpuTemp0/1000))
cpuTemp2=$(($cpuTemp0/100))
cpuTempM=$(($cpuTemp2 % $cpuTemp1))
#RPi4 has a different path to vcgencmd on bullseye
gpuTemp=$(/opt/vc/bin/vcgencmd measure_temp 2>/dev/null || /usr/bin/vcgencmd measure_temp 2>/dev/null)

# Function to write the temperature into the log
function writeToLog() {
        # Path to log file
        file="/home/pi/temp.log"

        # Check if the file exists
        if [ ! -f "$file" ] ; then
                # if not create the file
                touch "$file"
        fi

        echo "$1" >> "$file"
}

# Save the value with ISO 8601 timestamp
writeToLog "$(date --iso-8601=seconds) - CPU Temp: $cpuTemp1.$cpuTempM'C - GPU Temp: ${gpuTemp:5}"