Book Image

Learning Linux Shell Scripting - Second Edition

By : Ganesh Sanjiv Naik
Book Image

Learning Linux Shell Scripting - Second Edition

By: Ganesh Sanjiv Naik

Overview of this book

Linux is the most powerful and universally adopted OS. 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 reads this file and acts on commands as if they were typed on the keyboard. Learning Linux Shell Scripting covers Bash, GNU Bourne Again Shell, preparing you to work in the exciting world of Linux shell scripting. CentOS is a popular rpm-based stable and secured Linux distribution. Therefore, we have used CentOS distribution instead of Ubuntu distribution. Linux Shell Scripting is independent of Linux distributions, but we have covered both types of distros. We start with an introduction to the Shell environment and basic commands used. Next, we explore process management in Linux OS, real-world essentials such as debugging and perform Shell arithmetic fluently. You'll then take a step ahead and learn new and advanced topics in Shell scripting, such as decision making, starting up a system, and customizing a Linux environment. You will also learn about grep, stream editor, and AWK, which are very powerful text filters and editors. Finally, you'll get to grips with taking backup, using other language scripts in Shell Scripts as well as automating database administration tasks for MySQL and Oracle. By the end of this book, you will be able to confidently use your own shell scripts in the real world.
Table of Contents (17 chapters)

Getting Started and Working with Shell Scripting

If you work with Linux, you will come across the shell. It's usually the first program you work with. Graphical user interface (GUI) usage has become very popular due to its ease of use. Those who want to take advantage of the power of Linux will use the shell program by default:

  • The shell is a program that provides the user with 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 the Unix OS. The chronology was as follows: The Unix operating system was developed by Ken Thomson and Dennis Ritchie in 1969. It was released in 1970. They rewrote 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–differences in processes
  • When not to use scripts
  • Various directories
  • Working more effectively with shell–basic commands
  • Working with permissions