002 Operate Running Systems

Tech Tutorial: Operate Running Systems for the Red Hat Certified System Administrator (RHCSA) #

Introduction #

In preparing for the Red Hat Certified System Administrator (RHCSA) exam, it’s essential to gain a thorough understanding of how to operate running systems. This component of the exam requires proficiency in managing systems day-to-day, handling services, processes, and system tuning. This tutorial will guide you through common tasks you’ll need to perform under this objective using only Red Hat Enterprise Linux (RHEL) commands and configurations.

Step-by-Step Guide #

1. Managing Services with systemctl #

systemctl is the primary tool for managing services on RHEL. It allows you to start, stop, restart, reload, enable, and disable services.

Starting and Stopping Services #

To start a service:

sudo systemctl start [service_name]

To stop a service:

sudo systemctl stop [service_name]

For example, to start and then stop the Apache HTTP Server:

sudo systemctl start httpd
sudo systemctl stop httpd

Enabling and Disabling Services #

To enable a service to start at boot:

sudo systemctl enable [service_name]

To disable it:

sudo systemctl disable [service_name]

For instance, to enable and then disable sshd:

sudo systemctl enable sshd
sudo systemctl disable sshd

2. Managing System Processes #

Understanding how to manage system processes is crucial. You can use ps, top, kill, and other utilities.

Viewing Active Processes #

To display active processes:

ps aux

To get a real-time display of system processes:

top

Killing Processes #

To stop a process, you first need its PID, which you can find using ps:

ps aux | grep [process_name]

Then, use kill to terminate the process by its PID:

sudo kill [PID]

For a forceful termination, use:

sudo kill -9 [PID]

3. System Tuning with tuned #

tuned is a dynamic adaptive system tuning daemon that tunes system settings dynamically depending on usage. To adjust system profiles for various scenarios like throughput or power consumption:

List Available Profiles #

tuned-adm list

Activate a Profile #

sudo tuned-adm profile [profile_name]

For example, to set the system for maximum performance:

sudo tuned-adm profile throughput-performance

4. Configuring Logging with rsyslog #

System logging is managed in RHEL with rsyslog. Configuring it correctly ensures that you have access to vital system and service logs.

Viewing Logs #

Logs are stored in /var/log/. For instance, to view system messages:

sudo less /var/log/messages

Configuring rsyslog #

Edit the configuration file to define what data gets logged and where:

sudo vi /etc/rsyslog.conf

You can add lines such as:

*.info;mail.none;authpriv.none;cron.none                /var/log/messages

This example directs all info-level messages to /var/log/messages, excluding mail, authpriv, and cron messages.

Conclusion #

The ability to operate running systems effectively is a fundamental skill for any Red Hat Certified System Administrator. This tutorial covered essential tasks such as managing services, handling system processes, tuning systems with tuned, and configuring system logging with rsyslog. Mastery of these skills will not only help you in your RHCSA exam but also in real-world scenarios where system reliability and performance are critical. Practice these commands and configurations to deepen your understanding and proficiency.