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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
Tools
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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

Limiting the number of entered characters

We do not need functionality in the scripts we have used so far, but we may need to ask users to hit any key to continue. At the moment, we have set it up in such a way that the variable is not populated until we hit the Enter key. Users have to hit Enter to continue. If we use the -n option followed by an integer, we can specify the characters to accept before continuing, we will set 1 in this case. Take a look at the following code extract:

#!/bin/bash
read -p "May I ask your name: " name
echo "Hello $name"
read -n1 -p "Press any key to exit"
echo
exit 0

Now, the script will pause after displaying the name until we press any key; literally, we can press any key before continuing, as we accept just 1 key stroke. Whereas, earlier we were required to leave the default behavior in place, as we could not know how long a entered name would be. We have to wait for the user to hit Enter.

Tip

Note that we add an additional echo...

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