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

Basic script using read

When used as a part of a script that prompts for user input, the suppression of the line feed is exactly what we want. We will begin by copying the existing script to and build an interactive script. Initially, we will use echo as the prompt mechanism but as we gradually enhance the script, we will generate the prompt directly from the shell built-in read command:

$ cp $HOME/bin/ $HOME/bin/
$ chmod +x $HOME/bin/

Edit the $HOME/bin/ script so that it reads as the following:

echo -n "Hello I  $(basename $0) may I ask your name: "
echo "Hello $REPLY"
exit 0

As we execute the script, we will be greeted and prompted with our own name. This is echoed out using the $REPLY variable in the echo statement. As we have not yet supplied a variable name to the read built-in command the default $REPLY variable is used. The script execution and output is shown in the following screenshot. Take some time to practice...