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Mastering Linux Shell Scripting

You're reading from   Mastering Linux Shell Scripting Master the complexities of Bash shell scripting and unlock the power of shell for your enterprise

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Product type Paperback
Published in Dec 2015
Publisher
ISBN-13 9781784396978
Length 198 pages
Edition 1st Edition
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Author (1):
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Andrew Mallett Andrew Mallett
Author Profile Icon Andrew Mallett
Andrew Mallett
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Table of Contents (16) Chapters Close

Preface 1. 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 sed 9. Automating Apache Virtual Hosts 10. Awk Fundamentals 11. Summarizing Logs with Awk 12. A Better lastlog with Awk 13. Using Perl as a Bash Scripting Alternative 14. Using Python as a Bash Scripting Alternative Index

Chapter 3. Conditions Attached

I suppose we can say that we are now into the fine print of the script. These are the details that are written into our scripts using conditions to test if a statement should run or not. We are now ready to add some intelligence in scripts so our scripts become more robust, easier to use, and more reliable. Conditional statements can be written with simple command-line lists of AND or OR commands together or, more often, within traditional if statements.

In this chapter we will cover the following topics:

  • Simple decision paths using command-line lists
  • Verifying user input with lists
  • Using the test shell built-in
  • Creating conditional statements using if
  • Extending if with else
  • More conditions with elif
  • Creating the backup.sh script using elif
  • Using case statements
  • Script – front-end with grep
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