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The Ultimate Linux Shell Scripting Guide

You're reading from   The Ultimate Linux Shell Scripting Guide Automate, Optimize, and Empower tasks with Linux Shell Scripting

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Product type Paperback
Published in Oct 2024
Publisher Packt
ISBN-13 9781835463574
Length 696 pages
Edition 1st Edition
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Author (1):
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Donald A. Tevault Donald A. Tevault
Author Profile Icon Donald A. Tevault
Donald A. Tevault
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Table of Contents (26) Chapters Close

Preface 1. Getting Started with the Shell 2. Interpreting Commands FREE CHAPTER 3. Understanding Variables and Pipelines 4. Understanding Input/Output Redirection 5. Customizing the Environment 6. Text-Stream Filters – Part 1 7. Text Stream Filters – Part 2 8. Basic Shell Script Construction 9. Filtering Text with grep, sed, and Regular Expressions 10. Understanding Functions 11. Performing Mathematical Operations 12. Automating Scripts with here Documents and expect 13. Scripting with ImageMagick 14. Using awk – Part 1 15. Using awk – Part 2 16. Creating User Interfaces with yad, dialog, and xdialog 17. Using Shell Script Options with getops 18. Shell Scripting for Security Professionals 19. Shell Script Portability 20. Shell Script Security 21. Debugging Shell Scripts 22. Introduction to Z Shell Scripting 23. Using PowerShell on Linux 24. Other Books You May Enjoy
25. Index

Understanding stdin

This will be a bit easier, since only one operator symbol is involved. Here’s the graphical representation:

Figure 4.2: How stdin works

For our example, we’ll briefly look at the tr utility. (We’ll give tr a more in-depth explanation in Chapter 7, Text Stream Filters-Part 2. For now, let’s just say that it’s a utility that translates things.) By default, tr would take its stdin from the keyboard.

One thing you can do is to type a text string in all lower-case, and have tr echo it back to you in all upper-case. Hit the Enter key after you’ve typed the tr [:lower:] [:upper:] command, and hit it again after you’ve typed your line of text. When the upper-case line comes up, hit Ctrl-d to exit tr. It should look something like this:

[donnie@fedora ~]$ tr [:lower:] [:upper:]
i only want to type in all upper-case letters.
I ONLY WANT TO TYPE IN ALL UPPER-CASE LETTERS.
[donnie@fedora ~]$

If you...

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