How To : Optimize Log Maintenance on RHEL with Logrotate

The `logrotate` utility is a powerful and flexible tool for managing log files on Linux systems. It helps them save some disk space, as well as to avoid a potential risk of making a system unresponsive due to the lack of disk space.

1. How to use the logrotate utility on RHEL ?

To use `logrotate` on RHEL, you need to create a configuration file in the `/etc/logrotate.d/` directory for each log file that you want to rotate. The configuration file specifies how often to rotate the log file, how many rotated copies to keep, and what actions to take before and after rotation (e.g., compressing the log file). The `logrotate` command is typically run daily by the system's cron daemon to rotate the specified log files according to their respective configuration files.

2. Where the logrotate configuration files are stored ?

The `logrotate` configuration files are stored in the `/etc/logrotate.d/` directory. You can create a new configuration file in this directory by creating a text file with a descriptive name and a `.conf` extension, such as `/etc/logrotate.d/myapp.conf`.

3. How to set up a custom logrotate configuration ?

To set up a custom `logrotate` configuration, you'll need to create a new configuration file in the `/etc/logrotate.d/` directory. 

Here's an example configuration file that rotates a hypothetical `/var/log/myapp.log` file every day and keeps three rotated copies:

/var/log/myapp.log {

    daily

    rotate 3

    compress

    missingok

    notifempty

}

In this example, `daily` specifies that the log file should be rotated once per day, `rotate 3` specifies that only three rotated copies should be kept, `compress` specifies that rotated copies should be compressed with gzip, `missingok` specifies that it's okay if the log file is missing, and `notifempty` specifies that empty log files should not be rotated.

4. How to test a logrotate implementation ?

To test a `logrotate` implementation, you can use the `logrotate` command with the `-d` (debug) option, which will show you what actions `logrotate` would take without actually performing them. 

For example, to test the `myapp.conf` configuration file from the previous example, you could run:

logrotate -d /etc/logrotate.d/myapp.conf

This will show you what actions `logrotate` would take to rotate the `/var/log/myapp.log` file according to the specified configuration.