logrotate Command in Linux

Introduction to Log Management with Logrotate

In this practical guide, you'll discover how to effectively manage log files on your Linux system using the powerful logrotate command. This essential utility automates the process of rotating, compressing, and deleting older logs, ensuring optimal system health and performance. We'll begin with the fundamentals of logrotate, including version verification and understanding the default settings. Next, you'll learn to configure logrotate for Apache web server logs, tailoring the rotation parameters to suit your specific requirements.

Understanding the Logrotate Command

This section introduces the logrotate command, a crucial tool in Linux system administration. Logrotate streamlines log file management by automatically rotating, compressing, and removing outdated logs. This practice is vital for maintaining system stability, as unmanaged logs can rapidly consume significant disk space.

Let's start by verifying the installed logrotate version:

sudo logrotate --version

Example output:

logrotate 3.18.1

Now, let's explore the basic operation of the logrotate command. It utilizes the main configuration file, /etc/logrotate.conf, and any additional configurations found in the /etc/logrotate.d/ directory, to determine log rotation policies.

To view the default global configuration, execute:

sudo cat /etc/logrotate.conf

This will reveal the default settings controlling log rotation behavior, such as rotation frequency, the number of archived log files to retain, and the selected compression algorithm.

You can also manually trigger log rotation using the logrotate command. For instance, to rotate the Apache access log immediately, use:

sudo logrotate /etc/logrotate.d/apache2

This action will force a rotation of the Apache access log, irrespective of the configured schedule.

Configuring Logrotate for Apache Web Server

This section guides you through configuring logrotate to manage logs generated by the Apache web server.

First, ensure Apache is installed on your system:

sudo apt-get update
sudo apt-get install -y apache2

After installation, inspect the default Apache log files:

ls -l /var/log/apache2/

Example output:

-rw-r--r-- 1 root root   0 Apr 26 12:00 access.log
-rw-r--r-- 1 root root   0 Apr 26 12:00 error.log

Now, create a dedicated logrotate configuration file for Apache:

sudo nano /etc/logrotate.d/apache2

Populate the file with the following configuration:

/var/log/apache2/*.log {
    daily
    missingok
    rotate 7
    compress
    delaycompress
    notifempty
    create 640 root adm
    sharedscripts
    postrotate
        if /etc/init.d/apache2 status > /dev/null; then
            /etc/init.d/apache2 reload > /dev/null
        fi
    endscript
}

This configuration specifies that logrotate should:

  • Rotate Apache access and error logs on a daily basis.
  • Retain logs for a period of 7 days.
  • Compress archived log files to conserve disk space.
  • Create new log files with specific user, group, and permission settings.
  • Instruct Apache to reload its configuration after log rotation, ensuring seamless log writing to the new files.

To test the configuration, initiate a manual log rotation:

sudo logrotate /etc/logrotate.d/apache2

Then, verify the log directory to confirm the presence of rotated log files:

ls -l /var/log/apache2/

Example output:

-rw-r--r-- 1 root root   0 Apr 26 12:00 access.log
-rw-r--r-- 1 root root   0 Apr 26 12:00 error.log
-rw-r--r-- 1 root root   0 Apr 26 12:01 access.log.1.gz
-rw-r--r-- 1 root root   0 Apr 26 12:01 error.log.1.gz

Customizing Logrotate for Specific Log Files

In this section, you will learn to customize logrotate configurations for specific log files within your Linux environment.

We'll create a custom log file and configure logrotate to manage it.

First, create a sample log file:

sudo touch /var/log/custom.log
sudo chmod 644 /var/log/custom.log

Next, create a new logrotate configuration file for this custom log:

sudo nano /etc/logrotate.d/custom-logs

Add the following configuration:

/var/log/custom.log {
    weekly
    rotate 4
    compress
    delaycompress
    notifempty
    create 644 root adm
}

This configuration instructs logrotate to:

  • Rotate the custom.log file every week.
  • Maintain a history of 4 weeks of log files.
  • Compress the rotated log files for storage efficiency.
  • Create new log files with specific owner, group, and permissions.

To test this new configuration, trigger a manual log rotation:

sudo logrotate /etc/logrotate.d/custom-logs

Then, examine the log directory to confirm the creation of the rotated files:

ls -l /var/log/

Example output:

-rw-r--r-- 1 root adm     0 Apr 26 12:00 custom.log
-rw-r--r-- 1 root adm     0 Apr 19 12:00 custom.log.1.gz
-rw-r--r-- 1 root adm     0 Apr 12 12:00 custom.log.2.gz
-rw-r--r-- 1 root adm     0 Apr  5 12:00 custom.log.3.gz
-rw-r--r-- 1 root adm     0 Mar 29 12:00 custom.log.4.gz

You can extend this approach to customize logrotate for any log file on your system, including application-specific logs and other system logs, by creating individual configuration files in the /etc/logrotate.d/ directory. This allows for fine-grained control over log management for each service or application.

Conclusion

This tutorial provided a comprehensive introduction to the logrotate command in Linux, a tool vital for managing log files through automated rotation, compression, and deletion. You gained practical experience with the basic logrotate operations, including version checking, exploring default settings, and manually initiating log rotation. Furthermore, you learned how to configure logrotate for Apache web server logs, crafting custom configurations and understanding the various log rotation options available. This knowledge empowers you to maintain healthy and efficient Linux systems by effectively managing their log files.

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