Book Image

Mastering Linux Shell Scripting

By : Andrew Mallett
Book Image

Mastering Linux Shell Scripting

By: Andrew Mallett

Overview of this book

Shell scripting is a quick method to prototype a complex application or a problem by automating tasks when working on Linux-based systems. Using both simple one-line commands and command sequences complex problems can be solved with ease, from text processing to backing up sysadmin tools. In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Get to grips with the fundamentals of creating and running a script in normal mode, and in debug mode. Learn about various conditional statements' code snippets, and realize the power of repetition and loops in your shell script. Implement functions and edit files using the Stream Editor, script in Perl, program in Python – as well as complete coverage of other scripting languages to ensure you can choose the best tool for your project.
Table of Contents (21 chapters)
Mastering Linux Shell Scripting
About the Author
About the Reviewer

Creating operator menus

We can provide a menu to the Linux operators who need limited functionality from the shell and do not want to learn the details of command line use. We can use their login script to launch a menu for them. This menu will provide a list of command selections to choose from. The menu will loop until the user chooses to exit from the menu. We can create a new $HOME/bin/ script, the basis of the menu loop will be the following:

while true

The loop we have created here is infinite. The true command will always return true and loop continuously; however, we can provide a loop control mechanism to allow the user to leave the menu. To start building the structure of the menu, we will need to echo some text within the loop asking the user for their choice of command. We will clear the screen before the menu is loaded each time and an additional read prompt will appear after the execution of the desired command.

This allows the user to read the output from the...