Book Image

Mastering Linux Shell Scripting - Second Edition

By : Mokhtar Ebrahim, Andrew Mallett
5 (1)
Book Image

Mastering Linux Shell Scripting - Second Edition

5 (1)
By: Mokhtar Ebrahim, Andrew Mallett

Overview of this book

In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Grab your favorite editor and start writing your best Bash scripts step by step. 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. You will also learn to write complex shell scripts. This book will also deep dive into file system administration, directories, and system administration like networking, process management, user authentications, and package installation and regular expressions. Towards the end of the book, you will learn how to use Python as a BASH Scripting alternative. By the end of this book, you will know shell scripts at the snap of your fingers and will be able to automate and communicate with your system with keyboard expressions.
Table of Contents (17 chapters)

AWK control files

Just as with sed, we can simplify the command line by creating and including control files. This also makes editing the command later more easily achievable. The control files contain all the statements that we want awk to execute. The main thing that we must consider with sed, awk, and shell scripts is modularization; creating reusable elements that can be used to isolate and reuse the codes. This saves us time and work and we get more time for the tasks that we enjoy.

To see an example of an awk control file, we should revisit the formatting of the passwd file. Creating the following file will encapsulate the awk statements:

function green(s) { 
    printf "\033[1;32m" s "\033[0m\n" 
} 
BEGIN { 
    FS=":" 
    green("   Name:   UID:       Shell:") 
} 
{ 
    printf "%10s %4d %17s\n",$1,$3,$7 
} 

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