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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 5. Alternative Syntax

So far in the scripting journey, we have seen that we can use the test command to determine a conditional status. We have taken this a little further and discovered that we can also make use of the single square bracket. Here, we will recap the test command and look at the single square bracket in more detail. After having learned more about the square bracket, we will move onto more advanced variable or parameter management; thus, providing defaults and understating quoting issues.

Finally, we are going to see that within advanced shells like bash, korn, and zsh we can go with double brackets! Making use of the double round parenthesis and double square bracket can simplify the overall syntax and allow the standardization of the use of mathematical symbols.

In this chapter, we will cover the following topics:

  • Test conditions
  • Providing parameter defaults
  • When in doubt – quote!
  • Advanced tests using [[
  • Advanced tests using ((
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