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Mastering Bash

You're reading from   Mastering Bash A Step-by-Step Guide to working with Bash Programming and Shell Scripting

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Product type Paperback
Published in Jun 2017
Publisher Packt
ISBN-13 9781784396879
Length 502 pages
Edition 1st Edition
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Author (1):
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 Zarrelli Zarrelli
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Zarrelli
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Table of Contents (22) Chapters Close

Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
1. Let's Start Programming FREE CHAPTER 2. Operators 3. Testing 4. Quoting and Escaping 5. Menus, Arrays, and Functions 6. Iterations 7. Plug into the Real World 8. We Want to Chat 9. Subshells, Signals, and Job Controls 10. Lets Make a Process Chat 11. Living as a Daemon 12. Remote Connections over SSH 13. Its Time for a Timer 14. Time for Safety 1. Use in Real World Application

CLI, passing the arguments to the command line


Geopts is a Bash built-in widely used to parse switches and arguments passed on the command line of a script. We already saw other ways to this task, but getops makes it quite easy to handle it, since it can automatically recognize the switches and argument passed to the script. Its syntax is as follows:

getops options variable

The first thing we pass to getops is a string of options, the classical -a -x -f of whatever you want, without any leading dash, such asgetops axfor alsogetops ax:f. If you see an option followed by a colon, this means that the option is meant to have an argument such as follows:

./our_script.sh -x our_argument -a

In our example, -x has an argument while -a is a simple switch, or we can call it flag that can just be there or not, but it does not require any arguments. The options can be specified as lower or upper characters or digits. The getops built-in has some predefined variables for its internal use:

  • OPTARG holds...
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