Bash
|
Shell
|
Ubuntu

Bash Script Expunge/Clear Logs and Journal Debian/Ubuntu Compatible using Cron

This documentation provides step-by-step instructions on creating and implementing a shell script named clean-logs.sh on an Ubuntu/Debian 12 server. The purpose of this script is to reduce the overhead of log files and journal entries by truncating log files and clearing systemd journal logs older than one day.

1. Logging into Your Server

Step 1: Open Terminal

On your local machine, open the terminal application.

Step 2: Connect to Your Server

Use SSH to connect to your Ubuntu/Debian server. Replace your_server_ip with your server’s IP address:
ssh root@your_server_ip
If prompted, enter your root password.

Note: It is recommended that SSH keys be used for more secure authentication.

2. Creating the Clean-Logs Script

Step 1: Navigate to the Appropriate Directory

Once logged in as root, navigate to the directory where you want to store your script. Typically, scripts are stored in /usr/local/bin:
cd /usr/local/bin

Step 2: Create the Script File

Use a text editor like nano to create the clean-logs.sh script:
nano clean-logs.sh

Step 3: Write the Script

Copy and paste the following script into the editor:
Save and close the file by pressing CTRL + X, then Y, and Enter.

Step 4: Make the Script Executable

Change the script’s permissions to make it executable:
chmod +x clean-logs.sh

3. Understanding the Script

This script performs the following tasks:

Truncates Log Files: The script targets log files (*.log) in the /var/log directory and truncate them to 0 bytes. This means it empties the log files without deleting them, which helps maintain the structure while reducing disk usage.
Clears Systemd Journal Logs: It uses the journalctl --vacuum-time=1d command to remove systemd journal logs older than one day. This helps in freeing up space without losing recent logs.
Success Message: After performing the tasks, the script prints a message indicating successful execution.

4. Setting Up a Cron Job

Step 1: Open the Cron Table

To schedule this script to run automatically, you can add it to the cron table:
crontab -e

Step 2: Add the Cron Job

Scroll to the bottom of the file and add the following line to schedule the script to run daily at 2 AM:
0 2 * * * /usr/local/bin/clean-logs.sh > /dev/null 2>&1
Save and exit the editor.

Recommended Cron Times

Daily Cleanup: 2 AM is a typical time to perform maintenance tasks since server load is generally low.
Weekly Cleanup: If you prefer a weekly cleanup, you can adjust the cron schedule accordingly, e.g., every Sunday at 3 AM:
0 3 * * 0 /usr/local/bin/clean-logs.sh > /dev/null 2>&1

5. Testing the Script

Step 1: Run the Script Manually

To ensure the script works as expected, you can run it manually:
/usr/local/bin/clean-logs.sh
You should see the message: Log files cleared successfully!

Step 2: Check Log Files

After running the script, you can verify that the log files in /var/log have been truncated by checking their sizes:
ls -lh /var/log/*.log
The sizes should show 0 bytes if the truncation was successful.

6. Troubleshooting

If the script does not run as expected, ensure the paths are correct and the script has executable permissions.
Check the cron logs to verify that the job is being executed:
grep CRON /var/log/syslog

Conclusion

By following this documentation, you’ve set up a clean-logs.sh Script to manage your server’s log files efficiently. Regularly clearing logs helps reduce disk usage and ensures your server runs smoothly without unnecessary overhead.

Type: BASH

#!/bin/bash

# List of directories containing log files
LOG_DIRS=(
    "/var/log"
)

# Loop through each directory and clear the log files
for DIR in "${LOG_DIRS[@]}"; do
    find "$DIR" -type f -name "*.log" -exec truncate -s 0 {} \;
done

# Optionally, you can clear systemd journal logs
journalctl --vacuum-time=1d

# Print a message
echo "Log files cleared successfully!"