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

The history behind awk

The awk command is a mainstay in the command suite in both Unix and Linux. The Unix command awk was first developed by Bell Labs in the 1970's and is named after the surnames of the main authors: Alfred Aho, Peter Weinberger, and Brian Kernighan. The awk command allows access to the awk programming language, which is designed to process data within text streams.

To demonstrate the programming language that is provided with awk, we should create a hello world program. We know this is compulsory for all languages:

$ awk 'BEGIN { print "Hello World!" }'

Not only can we see that this code will print the ubiquitous hello message, we can also generate header information with the BEGIN block. Later, we will see that we can create summary information with an END code block by allowing for a main code block.

We can see the output of this basic command in the following screenshot: