How to Check Raspberry Pi Temperature from the Terminal

Ben
Ben
@benjislab

Monitoring the temperature of your Raspberry Pi is crucial to ensure it operates within safe limits and to prevent overheating, which can lead to throttling and damage. This guide will show you how to check the temperature of your Raspberry Pi directly from the terminal, helping you keep your device running smoothly.

Equipment Needed

  • Raspberry Pi with Raspberry Pi OS installed
  • Internet connection
  • Access to the command line

Check Temperature Using Built-in Commands

Using vcgencmd

The Raspberry Pi comes with a built-in tool called vcgencmd that allows you to query various system parameters, including temperature.

  1. Open the Terminal:

    Access the terminal on your Raspberry Pi. You can do this directly on the device or remotely via SSH.

  2. Check the Temperature:

Run the following command to get the current temperature of your Raspberry Pi's CPU:

vcgencmd measure_temp`

The output will look something like this:

temp=45.2'C

Using /sys/class/thermal

You can also check the temperature by reading the value from the thermal zone files in the /sys directory.

  1. Open the Terminal:

    Access the terminal on your Raspberry Pi.

  2. Read the Temperature:

    Run the following command to read the temperature:

cat /sys/class/thermal/thermal_zone0/temp

The output will be in millidegrees Celsius. For example, if the output is 45200, it means the temperature is 45.2°C.

  1. Convert to Celsius:

If you prefer a more readable format, you can convert it to degrees Celsius:

echo $(($(cat /sys/class/thermal/thermal_zone0/temp) / 1000))'°C'

Using Python Script

For more advanced monitoring, you can use a Python script to periodically check and display the temperature.

  1. Create a Python Script:

Create a new Python script named check_temp.py:

nano check_temp.py
  1. Add the Following Code:
import time
    
    def get_cpu_temp():
        with open("/sys/class/thermal/thermal_zone0/temp", "r") as f:
            temp = f.read()
        return float(temp) / 1000
    
    while True:
        temp = get_cpu_temp()
        print(f"CPU Temperature: {temp:.2f}°C")
        time.sleep(5)

  1. Run the Script:

    Save and close the file, then run the script:

python3 check_temp.py

This script will display the CPU temperature every 5 seconds.

Automating Temperature Monitoring

Setting Up a Cron Job

You can automate temperature monitoring and logging using a cron job.

  1. Create a Logging Script:

Create a script named log_temp.sh:

nano log_temp.sh
  1. Add the Following Code:
#!/bin/bash
    temp=$(vcgencmd measure_temp)
    echo "$(date): $temp" >> /var/log/rpi_temp.log
  1. Make the Script Executable:
chmod +x log_temp.sh
  1. Set Up the Cron Job:

Open the cron table for editing:

crontab -e

Add the following line to log the temperature every hour:

0 * * * * /path/to/log_temp.sh

Save and exit the editor. The temperature will now be logged to /var/log/rpi_temp.log every hour.

Conclusion

Monitoring the temperature of your Raspberry Pi is essential to maintain its performance and longevity. By using the built-in commands, a Python script, or setting up automated logging with cron jobs, you can ensure your Raspberry Pi operates within safe temperature ranges. Whether you are running a simple project or a complex server, keeping an eye on the temperature helps prevent potential overheating issues.