Book Image

Bash Cookbook

By : Ron Brash, Ganesh Sanjiv Naik
Book Image

Bash Cookbook

By: Ron Brash, Ganesh Sanjiv Naik

Overview of this book

In Linux, one of the most commonly used and most powerful tools is the Bash shell. With its collection of engaging recipes, Bash Cookbook takes you through a series of exercises designed to teach you how to effectively use the Bash shell in order to create and execute your own scripts. The book starts by introducing you to the basics of using the Bash shell, also teaching you the fundamentals of generating any input from a command. With the help of a number of exercises, you will get to grips with the automation of daily tasks for sysadmins and power users. Once you have a hands-on understanding of the subject, you will move on to exploring more advanced projects that can solve real-world problems comprehensively on a Linux system. In addition to this, you will discover projects such as creating an application with a menu, beginning scripts on startup, parsing and displaying human-readable information, and executing remote commands with authentication using self-generated Secure Shell (SSH) keys. By the end of this book, you will have gained significant experience of solving real-world problems, from automating routine tasks to managing your systems and creating your own scripts.
Table of Contents (15 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Writing one-line conditional statements and loops


In this recipe, we are going to write scripts that will contain one-line conditional statements as well as looping statements.

 

Getting ready

You need to have basic knowledge of conditional and looping statements.

How to do it...

Now we will write a script for a one-line conditional statement. In this script, we will write a simple if condition. Create a script named if_oneline.sh and write the following code in it:

a=100
if [ $a -eq 100 ]; then echo "a is equal to $a"; fi

Next, we will write a script for a one-line loop statement. In it, we are going to write a command that will execute 10 times. Create a script for_online.sh, and write this code in it.

for i in {1..10}; do echo "Hello World"; done

Now, we will write a script for a one-line while statement. This will be an infinite loop. Create a script named while_oneline.sh and write the following code in it:

x=10
while [ $x -eq 10 ]; do echo $x; sleep 2; done

How it works...

In this recipe, we wrote...