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The Ultimate Linux Shell Scripting Guide

The Ultimate Linux Shell Scripting Guide

By : Donald A. Tevault
4.8 (5)
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The Ultimate Linux Shell Scripting Guide

The Ultimate Linux Shell Scripting Guide

4.8 (5)
By: Donald A. Tevault

Overview of this book

Embark on a comprehensive journey through command shells with this hands-on manual. While Bash is a Linux staple, Z shell and PowerShell are rising stars, applicable to Linux, macOS, and Unix. Progress seamlessly through chapters, each building on the last, creating a solid foundation. Learn through a unique approach: concepts, examples, and interactive labs. These labs, nearly a hundred strong, form the core of experiential learning, essential for script creation. Focusing on Linux commands and their scripting applications, this manual is universally relevant across Linux and select Unix-like systems. It goes beyond theory, offering practical scripts for real-world Linux administration. Scripts are designed for manageability, aiding learning and troubleshooting. The goal is to nurture the ability to craft intelligent, functional shell scripts. While centered on Bash, this book offers a peek into the future with Z Shell and PowerShell, expanding your skills and adaptability. This book is systematically structured and engaging so that it will guide you to master command shells, equipping you for real-world Linux challenges.
Table of Contents (26 chapters)
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24
Other Books You May Enjoy
25
Index

Using Functions in Shell Scripts

You’ll be amazed at how functions can make your shell scripts so much more functional. (Yeah, I know. That really was a bad pun.) Read on to see how to make that happen.

Creating and Calling Functions

When you place a function inside a shell script, the function code won’t get executed until you call the function. Let’s modify the howdy_func.sh script to make that happen, like this:

#!/bin/bash
howdy ()
{
    echo "Howdy, world!";
    echo "How's it going?"
}
howdy

You see that all I had to do was to place the name of the function outside of the function code block. Also, note that the function definition must come before the function call. Otherwise, the shell will never be able to find the function. Anyway, when I run the script now, it works fine:

[donnie@fedora ~]$ ./howdy_func.sh
Howdy, world!
How's it going?
[donnie@fedora ~]$

I should also point out that the first curly...

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