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

Summary


In this chapter, we have looked at the Linux permissions scheme. We have learned that there are two main axes on which permissions are arranged: file permissions and file ownership. For file permissions, each file has an allowance (or disallowance) on read, write, and execute permissions. How these permissions work differs for files and directories. Permissions are applied by using ownership: a file is always owned by a user and a group. Besides the user and group, there are also file permissions present for everyone else, called the others ownership. If the user is either the owner or a member of the file's group, those permissions are available to the user. Otherwise, there need to be permissions for others to allow interaction with the file.

Next, we learned how to manipulate file permissions and ownership. By using chmod and umask, we were able to get the file permissions in the way we needed. Using sudo, chown, and chgrp, we manipulated the owner and group of a file. A warning...