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

Using grep to display text

Welcome back and welcome to the power of using regular expressions in the command line. We will be beginning this journey by looking at the grep command. This will enable us to grasp some simple concepts of searching through the text before moving onto more complex regular expressions and the editing file with sed.

Global Regular Expression Print (grep), or what we more commonly call the command grep, is a command line tool used to search globally (across all the lines in a file) and print the result to STDOUT. The search string is a regular expression.

The grep command is such a common tool that it has many simple examples and numerous occasions where we can use it each day. In the following section, we have included some simple and useful examples with explanations.

Displaying received data on an interface

In this example, we will print just the received data from the eth0 interface.


This is the interface that is my primary network connection to the Raspberry...