Neil Smyth - RHEL 8 Essentials

Red Hat Enterprise Linux 8 Essentials

Red Hat Enterprise Linux 8 Essentials

ISBN-13: 978-1-951442-04-0

2019 Neil Smyth / Payload Media, Inc. All Rights Reserved.

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Rev: 2.0

Table of Contents

Introduction

Arguably one of the most highly regarded and widely used enterprise level operating systems available today is the Red Hat Enterprise Linux (typically shortened to RHEL and pronounced rell ) distribution. Not only is it considered to be among the most stable and reliable operating systems, it is also backed by the considerable resources and technical skills of Red Hat, Inc.

RHEL 8 Essentials is designed to provide detailed information on the installation, use and administration of the Red Hat Enterprise Linux 8 distribution. For beginners, the book covers topics such as operating system installation, the basics of the GNOME desktop environment, configuring email and web servers and installing packages and system updates using App Streams. Additional installation topics such as dual booting with Microsoft Windows are also covered, together with all important security topics such as configuring a firewall and user and group administration.

For the experienced user, topics such as remote desktop access, the Cockpit web interface, logical volume management (LVM), disk partitioning, swap management, KVM virtualization, Secure Shell (SSH), Linux Containers and file sharing using both Samba and NFS are covered in detail to provide a thorough overview of this enterprise class operating system.

1.1 Superuser Conventions

RHEL 8, in common with Linux in general, has two types of user account, one being a standard user account with restricted access to many of the administrative files and features of the operating system, and the other a superuser ( root ) account with elevated privileges. Typically, a user can gain root access either by logging in as the root user, or using the su - command and entering the root password. In the following example, a user is gaining root access via the su - command:

[neil@rhel8-demo ~]$ su

Password:

[root@rhel8-demo ~]#

Note that the command prompt for a regular user ends with a $ sign while the root user has a # character. When working with the command-line, this is a useful indication as to whether or not you are currently issuing commands as the root user.

Alternatively, a single command requiring root privileges may be executed by a non-root user via the sudo command. Consider the following attempt to update the operating system with the latest patches and packages:

[neil@rhel8-demo ~]$ dnf update

Not root, Subscription Management repositories not updated

Error: This command has to be run under the root user.

Optionally, user accounts may be configured so that they have access to root level privileges. Instead of using the su - command to first gain root access, user accounts with administration privileges are able to run otherwise restricted commands using sudo .

[neil@rhel8-demo]$ sudo dnf update

We trust you have received the usual lecture from the local System

Administrator. It usually boils down to these three things:

#1) Respect the privacy of others.

#2) Think before you type.

#3) With great power comes great responsibility.

[sudo] password for neil:

Updating Subscription Management repositories.

.

.

The reason for raising this issue so early in the book is that many of the command-line examples outlined in this book will require root privileges. Rather than repetitively preface every command-line example with directions to run the command as root, the command prompt at the start of the line will be used to indicate whether or not the command needs to be performed as root. If the command can be run as a regular user, the command will be prefixed with a $ command prompt as follows:

$ date

If, on the other hand, the command requires root privileges, the command will be preceded by a # command prompt:

# dnf install openssh

1.2 Feedback

We want you to be satisfied with your purchase of this book. If you find any errors in the book, or have any comments, questions or concerns please contact us at .

1.3 Errata

While we make every effort to ensure the accuracy of the content of this book, it is inevitable that a book covering a subject area of this size and complexity may include some errors and oversights. Any known issues with the book will be outlined, together with solutions, at the following URL:

https://www.ebookfrenzy.com/errata/rhel8.html

In the event that you find an error not listed in the errata, please let us know by emailing our technical support team at . They are there to help you and will work to resolve any problems you may encounter.

A Brief History of Red Hat Linux

Red Hat Enterprise Linux is one of a number of variants (also referred to as distributions ) of the Linux operating system and is the product of a U.S. company named Red Hat, Inc., based in Raleigh, North Carolina. The company was founded in the mid-1990s through the merger of two companies owned at the time by Marc Ewing and Bob Young. The origins of Linux, however, go back even further. This chapter will outline the history of both the Linux operating system and Red Hat, Inc.

2.1 What exactly is Linux?

Linux is an operating system in much the same way that Windows is an operating system (and there any similarities between Linux and Windows end). The term operating system is used to describe the software that acts as a layer between the hardware in a computer and the applications that we all run on a daily basis. When programmers write applications, they interface with the operating system to perform such tasks as writing files to the hard disk drive and displaying information on the screen. Without an operating system, every programmer would have to write code to directly access the hardware of the system. In addition, the programmer would have to be able to support every single piece of hardware ever created to be sure the application would work on every possible hardware configuration. Because the operating system handles all of this hardware complexity, application development becomes a much easier task. Linux is just one of a number of different operating systems available today.

2.2 UNIX Origins

To understand the history of Linux, we first have to go back to AT&T Bell Laboratories in the late 1960s. During this time AT&T had discontinued involvement in the development of a new operating system named Multics. Two AT&T engineers, Ken Thompson and Dennis Ritchie, decided to take what they had learned from the Multics project and create a new operating system named UNIX which quickly gained popularity and wide adoption both with corporations and academic institutions.

A variety of proprietary UNIX implementations eventually came to market including those created by IBM (AIX), Hewlett-Packard (HP-UX) and Sun Microsystems (SunOS and Solaris). In addition, a UNIX-like operating system named MINIX was created by Andrew S. Tanenbaum designed for educational use with source code access provided to universities.