Perfect for beginners, Linux Essentials Exam students, and those seeking a career in IT, this book presents task-based lessons on the basics of Linux, including distributions, types of apps, freeware, licensing, operations, navigation, command functions, user types, users and groups, and much more.

Linux Essentials, 2nd Edition

Preface

The fact that you’re reading this book means you want to learn about the Linux operating system (OS). To begin this journey, you must first understand what an OS is and what type of OS Linux is. This chapter is therefore devoted to these basic issues.

Selecting an Operating System

Software is a type of intellectual property that is governed by copyright laws and, in some countries, patent laws. As a general rule, this makes it illegal to copy software unless you’re the software’s author. Open source software, however, relies on licenses, which are documents that alter the terms under which the software is released. As described in this chapter, open source licenses grant additional rights to software users.

Understanding Software Licensing

You can frequently select a product or technology on purely pragmatic grounds—what OS works well for a given task, which software suite is the least expensive, and so on. Sometimes, though, understanding the principles and philosophy that underlie a technology can be useful, and knowing these might even guide your choice.

Investigating Linux&rsquo;s Principles and Philosophy

This chapter begins a more hands-on look at Linux, as opposed to the more abstract information presented in the previous chapters. This chapter starts with a look at Linux desktop environments, including information on the most common desktop environments and their basic uses. If you’re using a desktop environment, chances are good that you’re doing so in order to run productivity software. Thus some common productivity packages for Linux are described. In addition, you likely will want to install additional productivity software, so software package management is briefly covered at the chapter’s end.

Using Common Linux Programs

Although Linux is software, it relies on hardware to operate. The capabilities and limitations of your hardware will influence the capabilities and limitations of Linux running on that hardware. Therefore, you should know these features for any computer that you use extensively or that you plan to buy.

Managing Hardware

You may think of the command line as an archaic relic from the 1970s, with not much relevance to computing today. Not so! Although Linux has numerous GUI programs, they’re mostly just flashy front ends to underlying text-mode tools. By learning those tools, you’ll be able to unlock Linux’s true power, enabling you to get your work done more quickly. You’ll also be able to manage should the Linux GUI system fail entirely, or should you need to log in and administer the system remotely. Command-line tools can also be scripted, meaning that you can write a simple program that performs a task more quickly or more easily than could be achieved using the standard programs alone. For these reasons, most of the chapters in this book describe both the GUI and command-line methods of getting things done.

Getting to Know the Command Line

Much of what you do with a computer involves manipulating files. Most obvious, files hold the correspondence, spreadsheets, digital photos, and other documents that you create. Files also hold the configuration settings for Linux—information on how to treat the network interfaces, how to access hard disks, and what to do as the computer starts up. Indeed, even access to most hardware devices and kernel settings is ultimately done through files. Knowing where to find the files and how to manage them is critically important for administering a Linux computer.

Managing Files

An important part of any OS’s job, including Linux, is the storage, management, and analysis of data. Data is valuable because of the knowledge that can be gleaned from it, so you need to be able to search and extract it properly, as well as to protect it. This chapter covers some of the tools that you can use to search, extract, and archive data.

Searching, Extracting, and Archiving Data

Computers are dynamic and multipurpose machines; they use many tools to do a variety of jobs. This chapter describes the ways that you can manage these tools. One aspect of this task is installing, uninstalling, and upgrading software packages. Another aspect of software management is in managing programs after they’re running. (Running programs are often called processes .) Finally, this chapter covers log files , which record details of what running programs do—particularly programs that run automatically and in the background.

Exploring Processes and Process Data

Computer documents come in many forms, but one of the most basic and flexible is a text file. Typically, configuration files and shell scripts are text files. Because you will often be modifying configuration files and creating shell scripts, you must be able to edit text files. This chapter covers this task with an emphasis on the simple text-mode pico , nano , and vi editors. A few roles played by text files are described first; then how to select a text editor is covered. To edit text files, of course, you must be able to start the editor, either on an existing document or a new one. The pico and nano editors are quite similar, so their operation is described together, followed by vi , which is a much more unusual editor by modern standards.

Editing Files

A script is a program written in an interpreted language, typically associated with a shell or a compiled program. In Linux, many scripts are shell scripts , which are associated with Bash or another shell. (If you’re familiar with batch files in Windows, scripts serve a similar purpose.) You can write shell scripts to help automate tedious, repetitive tasks or to perform new and complex tasks. Scripts perform many of Linux’s startup functions, so mastering scripting will help you manage the startup process.

Creating Scripts

Linux is a multiuser OS, meaning that it provides features to help multiple individuals use the computer. Collectively, these features constitute accounts . Previous chapters of this book have referred to accounts in passing but haven’t covered them in detail.

Understanding Basic Security

Linux is a multiuser OS, meaning that a single Linux computer can support many users, each with a unique account. With this capability comes the need to manage users’ accounts, and this chapter covers the procedures you’ll use to do so.

Creating Users and Groups

As a multiuser OS , Linux provides tools to help you secure your files against unwanted access—after all, you wouldn’t want another user to read your personal files or even delete your work files, whether accidentally or intentionally. Linux handles these tasks through two features of files and directories: their ownership and their permissions . Every file has an associated owner (an account with which it’s linked) and also an associated group. Three sets of permissions define what the file’s owner, members of the file’s group, and all other users can do with the file. Thus ownership and permissions are intertwined, although you use different text-mode commands to manipulate them. (GUI tools often combine the two, as described in this chapter.)

Setting Ownership and Permissions

Networking is a critical part of modern computing. Fortunately, most Linux distributions can often create a network connection automatically. On occasion, however, this process doesn’t work, or you may need to tweak the connection or debug problems when they occur. This chapter therefore covers network configuration.

Managing Network Connections

APPENDIX A: Answers to Review Questions

The purpose of the Linux Essentials Program is to define the basic knowledge required to use a desktop or mobile device competently using the Linux operating system. The program guides and encourages those who are new to Linux, and to open source in general, to understand the place of these tools in the context of the broader IT industry.

Community Questions