LPI Linux Essentials Study Guide

Exam 010 v1.6

Christine Bresnahan, Richard Blum

• Éditeur: Sybex
• Année: 2020
• ISBN:
  9781119657729
• Édition: 3
• Sujet: Informatique
• Sous-sujet: Systèmes d'exploitation

Provides a solid foundation forthose consideringa career in IT—covers the objectives of the new Linux Essentials Exam 010-160 v1.6

Linux is a secure, reliable, open source alternative to costly operating systems such as Microsoft Windows. As large organizations worldwide continue to add Linux servers, the need for IT professionals skilled in Linux continues to grow. The LPI Linux Essentials Study Guide is a valuable resource for anyone preparing to take the new Linux Essentials Exam—the entry-level certification from The Linux Professional Institute (LPI) which validates knowledge of Linux concepts and applications.

Written by recognized experts on Linux and open source technologies, this accessible, user-friendly guide covers desktop skills, the command line, directories and files, networks, scripting, security, users and permissions, and much more. Clear, concise chapters provide numerous hands-on tutorials, real-world examples, color illustrations, and practical end-of-chapter exercises and review questions. An ideal introduction for those new to Linux or considering a career in IT, this guide helps readers:

• Learn the operation and components of Linux desktops and servers
• Understand open source software, licensing, and applications
• Configure networks, security, cloud services, storage, and devices
• Create users and groups and set permissions and ownership
• Use the command line and build automation scripts

LPI Linux Essentials Study Guide: Exam 010 v1.6 is perfect for anyone beginning a career in IT, newcomers to Linux, students in computer courses, and system administrators working with other operating systems wanting to learn more about Linux and other open source solutions.

CHAPTER 1
Selecting an Operating System

Objectives:

• 
  1.1 Linux Evolution and Popular Operating Systems
• 
  4.1 Choosing an Operating System

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 Linux is and what an OS is. This chapter describes what an OS is, how users interact with an OS, how Linux compares to other popular OSs, and how even specific Linux implementations vary. Understanding these issues will help you as you make the switch to Linux and learn about the various Linux-based systems.

What Is an OS?

An OS provides all the fundamental features of a computer, at least from a software point of view. An OS enables you to use the computer’s hardware devices, defines the user interface standards, and provides basic tools that allow applications to run on the computer. This section describes the different parts that make up an OS and how they work together to create your computing experience.

What Is a Kernel?

An OS kernel is a software component responsible for managing various low-level features of the computer, including:

• Interfacing with hardware devices (network adapters, hard disks, and so on)
• Allocating memory to individual programs
• Allocating CPU time to individual programs
• Enabling programs to interact with one another

When you use a program (say, a web browser), it relies on the kernel for many of its basic functions. The web browser can communicate with the outside world only by using network functions provided by the kernel. The kernel allocates memory and CPU time to the web browser, without which it couldn’t run. The web browser may rely on plug-ins to display multimedia content; such programs are launched and interact with the web browser through kernel services. Any program you run on a computer relies on the kernel in a similar way, although the details vary from one OS to another and from one program to another.

The kernel is the software “glue” that holds the computer together. Without a kernel, a modern computer can do very little.

Kernels are not interchangeable; the Linux kernel is different from the macOS kernel used in Apple workstations and laptops, and from the Windows kernel used in Microsoft-compatible workstations and laptops. Each of these kernels uses a different internal design and provides different software interfaces for programs to use. Thus, each OS is built from the kernel up and uses its own set of programs that further define each OS’s features.

Some programs run on multiple kernels, but most need OS-specific tweaks. Programmers create binaries—the program files for a particular processor and kernel—for each OS. You need to run the binary file created for the specific OS you’re running the program on.

Linux uses a kernel called Linux—in fact, technically speaking, the word Linux refers only to the kernel. Other features that you might associate with Linux are provided by non-kernel programs, most of which are available on other platforms, as described shortly, in “What Else Identifies an OS?”

A student named Linus Torvalds created the Linux kernel in 1991. Linux has evolved considerably since that time. Today, it runs on a wide variety of CPUs and other hardware. The easiest way to learn about Linux is to use it on a desktop or laptop PC, so that’s the type of configuration emphasized in this book. The Linux kernel, however, runs on everything from tiny cell phones to powerful supercomputers.

What Else Identifies an OS?

The kernel is at the core of any OS, but it’s a component that most users don’t directly manipulate. Instead, most users interact with a number of other software components, many of which are closely associated with particular OSs. Such programs include the following:

Command-Line Shells Years ago, users interacted with computers exclusively by typing commands in a program (known as a shell) that accepted such commands. The commands would rename files, launch programs, and so on. Although many computer users today don’t use text-mode shells, they’re still important for intermediate and advanced Linux users, so we describe them in more detail in Chapter 5, “Getting to Know the Command Line,” and subsequent chapters rely heavily on your ability to use a text-mode shell. Many different shells are available, and which shells are available and popular differ from one OS to another. In Linux, a shell known as the Bourne Again Shell (Bash) is popular.

Graphical User Interfaces A graphical user interface (GUI) is an improvement on a text-mode shell, at least from the perspective of a beginning user. GUIs rely on icons, menus, and a mouse pointer rather than typed commands. Windows and macOS both have their own OS-specific GUIs. Linux relies on a GUI known as the X Window System, or X for short. X is a very basic GUI, so Linux also uses desktop environment program suites, such as the GNU Object Model Environment (GNOME) or the K Desktop Environment (KDE), to provide a more complete user experience. It’s the differences between a Linux desktop environment and the GUIs in Windows or macOS that will probab...