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Mastering Linux Shell Scripting

You're reading from   Mastering Linux Shell Scripting A practical guide to Linux command-line, Bash scripting, and Shell programming

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Product type Paperback
Published in Apr 2018
Publisher
ISBN-13 9781788990554
Length 284 pages
Edition 2nd Edition
Languages
Tools
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Authors (2):
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Mokhtar Ebrahim Mokhtar Ebrahim
Author Profile Icon Mokhtar Ebrahim
Mokhtar Ebrahim
Andrew Mallett Andrew Mallett
Author Profile Icon Andrew Mallett
Andrew Mallett
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Table of Contents (17) Chapters Close

Preface 1. The What and Why of Scripting with Bash FREE CHAPTER 2. Creating Interactive Scripts 3. Conditions Attached 4. Creating Code Snippets 5. Alternative Syntax 6. Iterating with Loops 7. Creating Building Blocks with Functions 8. Introducing the Stream Editor 9. Automating Apache Virtual Hosts 10. AWK Fundamentals 11. Regular Expressions 12. Summarizing Logs with AWK 13. A Better lastlog with AWK 14. Using Python as a Bash Scripting Alternative 15. Assessments 16. Other Books You May Enjoy

Creating conditional statements using if

As we have seen so far, it is possible to build simple conditions using command-line lists. These conditional statements can be written both with and without a test. As the complexity of the tasks increases, it becomes easier to create statements using if. This will certainly ease both the readability of the script and the logic layout. To a degree, it also matches the way in which we think and speak; if is a semantic in our spoken language in the same way it is within the bash script.

Even though it will take up more than a single line in the script, with an if statement we can achieve more and make the script more legible. That being said, let's look at creating if conditions. The following is an example of a script using an if statement:

#!/bin/bash 
# Welcome script to display a message to users on login 
# Author: @theurbanpenguin...
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