temp-mon.sh

#!/bin/bash
# Set up with a cron job to regularly check the CPU temperatures
# */5 * * * * /path/to/script.sh

# Alternatively, systemd timer
# [Unit]
# Description=Temperature monitor timer
# 
# [Timer]
# OnUnitActiveSec=5m
# Unit=temperature-monitor.service
# OnBootSec=5m
# 
# [Install]
# WantedBy=timers.target

# And service
# [Unit]
# Description=Temperature monitor
# After=network.target
# 
# [Service]
# Type=oneshot
# ExecStart=/bin/bash /usr/local/bin/temp-mon.sh
# 
# [Install]
# WantedBy=multi-user-wants.target


# Maximum temperature in degrees celcsius (as int)
MAX=40
# Time backoff (in seconds)
INTERVAL=3599

SENSORS=$(sensors);

# You may need to change the grep/awk depending on your setup
MATCH=$(echo "$SENSORS" | grep "Physical id 0" | awk '{print $4}')
TEMPC=${MATCH:1:2}

# Temperature is within range, all good.
if [ $TEMPC -lt $MAX ]; then
  exit 0
fi

if [ -e /tmp/temp-mon ]; then
  LASTSEND=$(cat /tmp/temp-mon);
else
  LASTSEND=0
fi

LASTSENDNICE=$(date --utc --date=@$LASTSEND)
PAYLOAD=`cat <<EOF
WARNING: $HOSTNAME is reporting a temperature of $TEMPC°C.
The configured threshold of this system is $MAX.
The last error was sent on $LASTSENDNICE

The output of the last sensors command was:
$SENSORS
EOF
`

CURTIME=$(date --utc +%s);
DIFFTIME=$(expr $CURTIME - $LASTSEND);

if [ $DIFFTIME -gt $INTERVAL ]; then
  echo $CURTIME > /tmp/temp-mon;
  echo "$PAYLOAD" | mail -s "CRITICAL: Temperature warning for $HOSTNAME" nanderson@nanderson.me
  echo "Mail sent!"
  # Send the message!
fi