Book Image

Learn Linux Shell Scripting – Fundamentals of Bash 4.4

By : Sebastiaan Tammer
Book Image

Learn Linux Shell Scripting – Fundamentals of Bash 4.4

By: Sebastiaan Tammer

Overview of this book

Shell scripts allow us to program commands in chains and have the system execute them as a scripted event, just like batch files. This book will start with an overview of Linux and Bash shell scripting, and then quickly deep dive into helping you set up your local environment, before introducing you to tools that are used to write shell scripts. The next set of chapters will focus on helping you understand Linux under the hood and what Bash provides the user. Soon, you will have embarked on your journey along the command line. You will now begin writing actual scripts instead of commands, and will be introduced to practical applications for scripts. The final set of chapters will deep dive into the more advanced topics in shell scripting. These advanced topics will take you from simple scripts to reusable, valuable programs that exist in the real world. The final chapter will leave you with some handy tips and tricks and, as regards the most frequently used commands, a cheat sheet containing the most interesting flags and options will also be provided. After completing this book, you should feel confident about starting your own shell scripting projects, no matter how simple or complex the task previously seemed. We aim to teach you how to script and what to consider, to complement the clear-cut patterns that you can use in your daily scripting challenges.
Table of Contents (24 chapters)
Title Page
About Packt
Contributors
Preface
Free Chapter
1
Introduction
Index

Error prevention


At this point, you should have a firm grasp on how we can handle (user input) error. Obviously, context is everything here: depending on the situation, some errors are handled in different ways. There is one more important subject in this chapter, and that is error prevention. While knowing how to handle errors is one thing, it would be even better if we can prevent errors during script execution altogether.

Checking arguments

As we noted in the previous chapter, when you're dealing with positional arguments passed to your script, a few things are very important. One of them is whitespace, which signifies the boundary between arguments. If we need to pass an argument to our script that contains whitespace, we need to wrap that argument in single or double quotes, otherwise it will be interpreted as multiple arguments. Another important aspect of positional arguments is getting exactly the right number of arguments: not too few, but definitely not too many either.

 

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