Book Image

Learning Linux Shell Scripting

By : Ganesh Sanjiv Naik
Book Image

Learning Linux Shell Scripting

By: Ganesh Sanjiv Naik

Overview of this book

Linux is the one of the most powerful and universally adopted OSes. Shell is a program that gives the user direct interaction with the operating system. Scripts are collections of commands that are stored in a file. The shell can read this file and act on the commands as if they were typed on the keyboard. Shell scripting is used to automate day-to-day administration, and for testing or product development tasks. This book covers Bash, GNU Bourne Again SHell, preparing you to work in the exciting world of Linux shell scripting. We start with an introduction to the Shell environment and explain basic commands used in Shell. Next we move on to check, kill, and control the execution of processes in Linux OS. Further, we teach you about the filter tools available in Linux and explain standard output and standard errors devices. Then we will ensure you understand Shell’s interpretation of commands and get a firmer grasp so you use them in practice. Next, you’ll experience some real-world essentials such as debugging and perform Shell arithmetic fluently. Then you’ll take a step ahead and learn new and advanced topics in Shell scripting, such as starting up a system and customizing a Linux system. Finally, you’ll get to understand the capabilities of scripting and learn about Grep, Stream Editor, and Awk.
Table of Contents (20 chapters)
Learning Linux Shell Scripting
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Chapter 1. Getting Started and Working with Shell Scripting

Whoever works with Linux will come across shell as the first program to work with. The Graphical user interface (GUI) usage has become very popular due to the ease of use. Those who want to take advantage of the power of Linux will use the shell program by default.

Shell is a program which provides the user direct interaction with the operating system. Let's understand the stages in the evolution of the Linux operating system. Linux was developed as a free and open source substitute for UNIX OS. The chronology can be as follows:

  • The UNIX operating system was developed by Ken Thomson and Dennis Ritchie in 1969. It was released in 1970. They rewrote the UNIX using C language in 1972.

  • In 1991, Linus Torvalds developed the Linux kernel for the free operating system.

In this chapter, we will cover the following topics:

  • Comparison of shells

  • Working in shell

  • Learning basic Linux commands

  • Our first script—Hello World

  • Compiler and interpreter—difference in process

  • When not to use scripts

  • Various directories

  • Working more effectively with shell—basic commands

  • Working with permissions