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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 Conditional Statements

You’ve already been using if constructs without even knowing it. That’s because you don’t have to explicitly declare them as such. The simple /kernel/ command that you just saw in the awk_kernel1.awk script means that if the kernel string is found on a line, then print that line. However, awk also offers the whole array of programming constructs that you would expect to see in other languages. For example, let’s create the awk_kernel2.awk script, which will look like this:

#!/usr/bin/awk -f
{
        if (/kernel/) {
                print $0
        }
}

This is somewhat different from what you’re used to seeing in bash scripts, because in awk there’s no need to use then or fi statements. This is because awk uses C language syntax for its programming constructs. So, if you’re used to programming in C, rejoice!

Also, note how you need to surround the pattern with a pair of parentheses, and how...

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