A Shell Script to Send Email Alert When Memory Gets Low

As we use our computers for various tasks, we often run multiple applications and software that consume a significant amount of memory. When available memory gets low, it can cause our computer to slow down or even crash. To avoid this situation, we can use a shell script to send an email alert when memory gets low. In this article, we'll discuss how to create such a shell script and explain how it works.

Understanding Shell Scripts

Before we dive into creating a shell script, let's first understand what shell scripts are. A shell script is a program that consists of a series of commands written in a shell language, which is interpreted by the operating system. Shell scripts are commonly used to automate repetitive tasks and system administration tasks.

Creating a Shell Script to Monitor Memory Usage

To create a shell script to monitor memory usage, we need to use the following commands

• free This command displays the amount of free and used memory in the system.

• awk This command is a powerful text-processing tool that allows us to manipulate and analyze data.

• mail This command sends an email to a specified email address.

Here is the shell script that we'll create

#!/bin/bash
# Get memory usage details
memory=$(free -m | awk 'NR==2{printf "%.2f%%", $3*100/$2}')
# Define threshold memory usage
threshold=80.00
# Check if memory usage is greater than threshold
if (( $(echo "$memory > $threshold" | bc -l) )); then
   # Send an email alert
   echo "Memory usage is above threshold: $memory" | mail -s "Memory Usage Alert" your_email_address@example.com
fi

Script Breakdown

Let's go through this script line by line to understand what it does

• #!/bin/bash This line tells the operating system to use the Bash shell to interpret the script.

• memory=$(free -m | awk 'NR==2{printf "%.2f%%", $3*100/$2}') This line gets memory usage details using the free command and calculates the percentage of used memory using the awk command.

• threshold=80.00 This line defines the threshold memory usage. In this example, we've set the threshold to 80%.

• if (( $(echo "$memory > $threshold" | bc -l) )); then This line checks if memory usage is greater than the threshold using an if statement.

• echo "Memory usage is above threshold: $memory" | mail -s "Memory Usage Alert" your_email_address@example.com If memory usage is above the threshold, this line sends an email alert to the specified email address using the mail command.

Using the Shell Script

To use the shell script, we need to follow these steps

• Open a text editor and copy the script code into it.

• Replace "your_email_address@example.com" with your actual email address.

• Save the file with a .sh extension (e.g., mem_alert.sh).

• Open a terminal and navigate to the directory where you saved the file.

• Make the file executable by running the following command

chmod +x mem_alert.sh

• Run the shell script using the following command

./mem_alert.sh

The shell script will now monitor memory usage and send an email alert if usage goes above the threshold.

Setting Up Automated Monitoring

To continuously monitor memory usage, you can set up a cron job to run the script at regular intervals

# Edit crontab
crontab -e

# Add this line to run every 5 minutes
*/5 * * * * /path/to/mem_alert.sh

Customizing the Shell Script

You can customize the shell script to suit your needs by modifying the following variables

• threshold You can change the threshold memory usage by modifying the value of the threshold variable. For example, if you want to set the threshold to 90%, you can change the line "threshold=80.00" to "threshold=90.00".

• email_address You can change the email address to which the alert is sent by replacing "your_email_address@example.com" with your desired email address.

You can also modify the message that is sent in the email alert by changing the echo statement. For example, you can add more information to the message or customize the subject of the email alert.

Benefits of Using a Shell Script to Monitor Memory Usage

Conclusion

In this article, we discussed how to create a shell script to monitor memory usage and send email alerts when memory usage goes above a threshold. We explained the various commands used in the shell script and provided step-by-step instructions on how to use and customize the script. By using a shell script to monitor memory usage, you can automate the monitoring process and take proactive measures to avoid issues related to low memory.