Script for use with M/Monit to monitor system temperature

SystemTemp.sh

#!/bin/sh -e
##
## Title:                     SystemTemp.sh
## Description:               Script for use with M/Monit to monitor system temperature
## Author:                    B. van wetten
## Created date:              22-01-2020
## Updated date:              23-01-2020
## Version:                   0.2
## GitHub Gist:               https://gist.github.com/QNimbus/b2ead8cde75bcf9b177b1a9d951d9411
##
## Usage:                     SystemTemp.sh [max_temp]
## Sample M/Monit condition:  status != 0 for 3 times within 5 cycles
## Notes:                     Exit code 0 when temperature is greater than 'max_temp'
##                            otherwise exitcode is equal to system temperature.
##                            If no command line parameter is supplied 'max_temp' equals 40 degrees

MaxSystemTemp=${1:-40}
CurrentSensor=0
NumSensors=`sysctl hw.acpi.thermal | egrep "hw.acpi.thermal.tz[0-9]" | cut -d "." -f-4 | sort --unique | wc -l`
ExitCode=0

while [ $CurrentSensor -lt $NumSensors ]
do
   SystemTemp=`sysctl hw.acpi.thermal.tz${CurrentSensor}.temperature 2> /dev/null | awk '{print $2}' | awk -F. '{print $1}'`
   echo "System thermal zone ${CurrentSensor} sensor temperature: ${SystemTemp}"

   if [ $? -eq 0 ] && [ $SystemTemp -gt $MaxSystemTemp ] && [ $SystemTemp -gt $ExitCode ]
   then
      ExitCode=$SystemTemp
   fi

   CurrentSensor=$((CurrentSensor+1))
done

echo "Maximum system thermal zone temperature allowed: ${MaxSystemTemp}"

exit $ExitCode