Question

Write a Python code that when the temperature of the CPU in the raspberry pi exceeds 40 degrees Celsius you receive an email.

Answer 1

# coding=utf-8
import os
import smtplib
from email.mime.text import MIMEText

critical = False
high = 40
too_high = 45

# At First we have to get the current CPU-Temperature with this defined function
def getCPUtemperature():
    res = os.popen('vcgencmd measure_temp').readline()
    return(res.replace("temp=","").replace("'C\n",""))

# Now we convert our value into a float number
temp = float(getCPUtemperature())

# Check if the temperature is abouve 60°C (you can change this value, but it shouldn't be above 70)
if (temp > high):
    if temp > too_high:
        critical = True
        subject = "Critical warning! The temperature is: {} shutting down!!".format(temp)
        body = "Critical warning! The actual temperature is: {} \n\n Shutting down the pi!".format(temp)
    else:
        subject = "Warning! The temperature is: {} ".format(temp)
        body = "Warning! The actual temperature is: {} ".format(temp)

    # Enter your smtp Server-Connection
    server = smtplib.SMTP('localhost', 25) # if your using *mail: smtp.*mail.com
    server.ehlo()
    server.starttls()
    server.ehlo
    # Login
    # server.login("your email or username", "your Password")
    
    msg = MIMEText(body)
    msg['Subject'] = subject
    msg['From'] = "Root"
    msg['To'] = "root"

    # Finally send the mail
    server.sendmail("root", "root", msg.as_string())
    server.quit()
    
    # Critical, shut down the pi
    if critical:
        os.popen('sudo halt')

# Don't print anything otherwise. 
# Cron will send you an email for any command that returns "any" output (so you would get another  email)
# else:
#   print "Everything is working fine!"

it will send a mail as soon as it crosses 40'C

I've tweaked it a little bit to also shut down the pi in case the temp is too high (45'C in my case).

To make this as a cronjob running every 30 min do this

mkdir -p ~/scripts
vi ~/scripts/temp.py

paste the code from the script above.

Then crontab -e and add this:

30 * * * * python ~/scripts/temp.py

close crontab editor (ctrl-x if nano or esc, then :wq if vim)

That's it