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

Advanced permissions


This covers the basic permissions for Linux. There are, however, some advanced topics that we'd like to point out, but we will not be discussing them at length. For more information on these topics, check the Further reading section at the end of this chapter. We have included a reference for file attributes, special file permissions, and access control lists.

File attributes

Files can also have attributes that are expressed in another way than the permissions we have seen so far. An example of this is making a file immutable (a fancy word, which means it cannot be changed). An immutable file still has normal ownership and group and RWX permissions, but it will not allow the user to change it, even if it contains the writable permission. Another characteristic of this is that the file cannot be renamed.

Other file attributes include undeletable, append only, and compressed. For more information on file attributes, check the man pages for the lsattr and chattr commands ...