Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By : Richard Blum, Christine Bresnahan
Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By: Richard Blum, Christine Bresnahan

Overview of this book

The Linux command line enables you to type specific shell commands directly into the system to manipulate files and query system resources. Command line statements can be combined into short programs called shell scripts, a practice increasing in popularity due to its usefulness in automation. Linux is a robust system with tremendous potential, and Linux Command Line and Shell Scripting Bible opens the door to new possibilities. Linux Command Line and Shell Scripting Bible is your essential Linux guide. It contains new functional examples that are fully updated to align with the latest Linux features. Beginning with command line fundamentals, the book moves into shell scripting and shows you the practical application of commands in automating frequently performed functions. This book is a complete guide providing detailed instruction and expert advice working within this aspect of Linux. Whether used as a tutorial or as a quick reference, this book contains information that every Linux user should know.
Table of Contents (34 chapters)
Part I: The Linux Command Line
Part II: Shell Scripting Basics
Part III: Advanced Shell Scripting
Part IV: Creating Practical Scripts
End User License Agreement

Creating Text Menus

The most common way to create an interactive shell script is to utilize a menu. Offering your customers a choice of various options helps guide them through exactly what the script can and can't do.

Menu scripts usually clear the display area and then show a list of options available. The customer can select an option by pressing an associated letter or number assigned to each option. Figure 18.1 shows the layout of a sample menu.


Figure 18.1 Displaying a menu from a shell script

The core of a shell script menu is the case command (see Chapter 12). The case command performs specific commands, depending on what character your customer selects from the menu.

The following sections walk you through the steps you should follow to create a menu-based shell script.

Create the menu layout

The first step in creating a menu is, obviously, to determine what elements you want to appear in the menu and lay them out the way that you want them to appear.

Before creating...