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

Manipulating file permissions and ownership


After reading the first part of this chapter, you should have a decent understanding of Linux file permissions, and how read, write, and executed are used on a user, group, and other levels to ensure that files are exposed exactly as required. However, up until this point, we've been dealing with static permissions. When administering a Linux system, you will most likely spend a fair bit of time adjusting and troubleshooting permissions. In this part of the book, we'll be exploring the commands we can use to manipulate the permissions on files.

chmod, umask

Let's circle back to our testfile. It has the following permissions: -rw-rw----. Read/writable by user and group, readable by others. While these permissions might be fine for most files, they are definitely not a great fit for all files. What about private files? You would not want those to be readable by everyone, perhaps not even by group members.

The Linux command to change permissions on a...