The Ultimate Linux Shell Scripting Guide: Automate, Optimize, and Empower tasks with Linux Shell Scripting

Donald A. Tevault

R$80 ~~R$200.99~~

4.8 (4 Ratings)

eBook Oct 2024 696 pages 1st Edition

Donald A. Tevault

R$80 ~~R$200.99~~

4.8 (4 Ratings)

eBook Oct 2024 696 pages 1st Edition

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The Ultimate Linux Shell Scripting Guide

Getting Started with the Shell

Before we can talk about shell scripting, we need to know what a shell is and what kinds of shells are available for Linux, Unix, and Unix-like operating systems. We’ll also talk about other important topics that will help get you started in the wide, wonderful world of shell scripting.

Topics in this chapter include:

Understanding shells
Finding help with shell commands
Using a text editor
Understanding compiled versus interpreted programming
Understanding root and sudo privileges

If you’re ready, let’s get started on this important journey. And, always remember to have some fun along the way.

Understanding Shells

So, you’re scratching your head and saying, “What is a shell, and why should I care?” Well, a shell is a program that acts as an intermediary between the user and the operating system kernel. A user types commands into the shell, which passes them into the kernel for processing. The output is then presented to the user via the computer terminal, which can also referred to as the screen. The most common shell on Linux systems is bash, but the Z shell (zsh) has been gaining popularity in recent years. (I’ll explain why in Chapter 22, Using the Z Shell.) You’ll find bash as the default shell on most Linux distros and certain Unix-like distros such as OpenIndiana, and zsh as the default on Kali Linux.

If you are brand new to the wild, wonderful world of Linux and its Unix or Unix-like cousins, you might be wondering what a distro is. Well, unlike Windows and macOS, which are proprietary and controlled by a single company, Linux and its cousins are primarily open source software, which means that anyone can take the source code and create their own implementations, or distributions. Red Hat Enterprise Linux, Fedora, and Ubuntu are examples of Linux distributions, and OpenIndiana and FreeBSD are examples of Unix-like distributions. But, we hard-core geeks rarely utter the word distribution, and instead just say distro, for short.

Also, the reason that I differentiate between Unix and Unix-like distros has to do with legal reasons that date back to the 1980s. This involves a rather complicated mess that I would rather not go into here. Suffice it to say that the creators of distros such as FreeBSD are not allowed to refer to their creations as Unix, even though they are mostly functionally equivalent. But, they can say that their creations are Unix-like.

The newest versions of macOS also have zsh set as the default shell. Fortunately, much of what you’ll learn about bash also works on zsh. The main difference is that zsh has a few cool features that bash doesn’t have. (Again, I’ll explain all about that in Chapter 22.) PowerShell, which originally was only available for Microsoft Windows operating systems, has also been available for Linux and macOS since 2016. PowerShell is a whole different animal, but you might find it quite useful, as you should see when we get to Chapter 23, Using PowerShell on Linux.

It’s common to hear people refer to bash as the bash shell. But, bash is short for Bourne Again Shell. So, when you say bash shell, you’re really saying Bourne Again Shell Shell, which is a bit awkward. This is the same as when people talk about going to the ATM machine to withdraw some money. What they’re really saying is that they’re going to the Automatic Teller Machine Machine, which is also awkward.

And, don’t even get me started on the people who talk about hot water heaters. I mean, if the water is already hot, why heat it?

On the other hand, if you find that you still need to say bash shell so that people will know what you’re talking about, I’ll understand and won’t condemn you for it. In fact, you might even see me do that on occasion.

The coolest thing about modern operating system shells is that they’re much more than just an interface tool. They’re also full-blown programming environments with many of the same programming constructs as more complex programming languages, such as Pascal, C, or Java. Systems administrators can make their jobs much easier by using shell scripts to automate complex, repetitive tasks.

When you log into a text-mode Linux or Unix server, you’ll be presented with a black screen and some text, which looks like this:

Figure 1.1: Plain bash on a text-mode Debian Linux machine

This is the unadorned, plain-jane shell. Machines with desktop environments installed will interface with the shell via a terminal emulator, which will look something like this:

Figure 1.2: A terminal emulator that interfaces with bash on an OpenIndiana machine

The name of the terminal emulator will differ from one desktop environment to the next, but all do the same job. The advantage of using a terminal emulator is that you’ll have the luxury of using scroll bars, customizing the display, and using copy-and-paste for the command-line.

In any case, you can see which shell you’re using by typing:

donnie@fedora:~$ echo $SHELL
/bin/bash
donnie@fedora:~$

In this case, you see that you’re using bash.

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Key benefits

Develop portable scripts using Bash, Zsh, and PowerShell that work seamlessly across Linux, macOS, and Unix systems
Progress seamlessly through chapters with clear concepts, practical examples, and hands-on labs for skill development
Build real-world Linux administration scripts, enhancing your troubleshooting and management skills

Description

Dive into the world of Linux shell scripting with this hands-on guide. If you’re comfortable using the command line on Unix or Linux but haven’t fully explored Bash, this book is for you. It’s designed for programmers familiar with languages like Python, JavaScript, or PHP who want to make the most of shell scripting. This isn’t just another theory-heavy book—you’ll learn by doing. Each chapter builds on the last, taking you from shell basics to writing practical scripts that solve real-world problems. With nearly a hundred interactive labs, you’ll gain hands-on experience in automation, system administration, and troubleshooting. While Bash is the primary focus, you'll also get a look at Z Shell and PowerShell, expanding your skills and adaptability. From mastering command redirection and pipelines to writing scripts that work across different Unix-like systems, this book equips you for real-world Linux challenges. By the end, you'll be equipped to write efficient shell scripts that streamline your workflow and improve system automation.

Who is this book for?

This book is for programmers who use the command line on Unix and Linux servers already, but don't write primarily in Bash. This book is ideal for programmers who've been using a scripting language such as Python, JavaScript or PHP, and would like to understand and use Bash more effectively. It’s also great for beginning programmers, who want to learn programming concepts.

What you will learn

Grasp the concept of shells and explore their diverse types for varied system interactions
Master redirection, pipes, and compound commands for efficient shell operations
Leverage text stream filters within scripts for dynamic data manipulation
Harness functions and build libraries to create modular and reusable shell scripts
Explore the basic programming constructs that apply to all programming languages
Engineer portable shell scripts, ensuring compatibility across diverse platforms beyond Linux

Product Details

Publication date, Length, Edition, Language, ISBN-13

Publication date : Oct 18, 2024

Length: 696 pages

Edition : 1st

Language : English

ISBN-13 : 9781835463154

Vendor :

Linux Foundation

Category :

Security , Cloud & Networking

Languages :

Bash

Concepts :

Cybersecurity , System Administration

Tools :

Linux

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Download this book in EPUB and PDF formats

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A. Zubarev Oct 24, 2024

This book is probably one of, if not the most, comprehensive of all on the capabilities of scripting on Linux.It covers all the common scripting shells, even PowerShell (who knew it would be possible to run Microsoft's shell on Linux?!), methods of securing scripts, text manipulation, advanced scripting techniques including automation, shell configuration, error handling, piping and much more.I especially liked the chapters on image manipulations and creating user interfaces.Be aware that this book assumes you are scripting for an on-prem resident machine and it is probably the only shortcoming I can mention.

Amazon Verified review

N/A Jan 30, 2025

Feefo Verified review

Byron Gorman Nov 15, 2024

The Ultimate Linux Shell Scripting, is an extremely fascinating read. So let’s get right to the contents of the book. First the book sets you up for success by providing you with examples of code, that you will use with the hands on labs that personally I found to be intriguing. This allows the reader to jump into the thick of Linux from the start. The labs are presented so the reader can have a better understanding of the processes and code automation, the rich contents covers everything from learning the shell and shell emulators to using Powershell on Linux and macOS. This allows the reader the opportunity to explore Linux using several different flavors. Starting with the shell you will learn simple commands that will show you the difference between the regular user and the root user. Then we step into commands and how to leverage them in your favor. By automating some Linux scripts you will be able to customize your environment and do global configurations.The book also allows you to create basic shell scripts, and filter them and the steps you through advanced scripts. This read is full of examples and illustrations that show how the script commands are used and the end result you should be seeing.At the end of each chapter there are review questions to make certain that you have maintained the correct information.If you are new to Linux, attempting to get your certification or are a seasoned Linux user this is one book to add to you’re personal Linux war chest. I added it to mine! Read more

Emiru Mar 01, 2025

I am giving 4 stars because i am still on chapter 2 but I love the writer's approach to the subject matter. I have been using Linux now for 10+ years and the teaching style has knowledge for every level.

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The Ultimate Linux Shell Scripting Guide: Automate, Optimize, and Empower tasks with Linux Shell Scripting

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Getting Started with the Shell

Understanding Shells

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