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  • Book Overview & Buying The Ultimate Linux Shell Scripting Guide
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The Ultimate Linux Shell Scripting Guide

The Ultimate Linux Shell Scripting Guide

By : Donald A. Tevault
4.9 (7)
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The Ultimate Linux Shell Scripting Guide

The Ultimate Linux Shell Scripting Guide

4.9 (7)
By: Donald A. Tevault

Overview of this book

Dive into the world of Linux shell scripting with this hands-on guide. If you’re comfortable using the command line on Unix or Linux but haven’t fully explored Bash, this book is for you. It’s designed for programmers familiar with languages like Python, JavaScript, or PHP who want to make the most of shell scripting. This isn’t just another theory-heavy book—you’ll learn by doing. Each chapter builds on the last, taking you from shell basics to writing practical scripts that solve real-world problems. With nearly a hundred interactive labs, you’ll gain hands-on experience in automation, system administration, and troubleshooting. While Bash is the primary focus, you'll also get a look at Z Shell and PowerShell, expanding your skills and adaptability. From mastering command redirection and pipelines to writing scripts that work across different Unix-like systems, this book equips you for real-world Linux challenges. By the end, you'll be equipped to write efficient shell scripts that streamline your workflow and improve system automation.
Table of Contents (27 chapters)
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26
Index

Using uniq

Use the uniq utility with files that have consecutive, identical lines. Its default behavior is to only show one copy of any line that is duplicated. Let’s begin by creating the fruit.txt file, like so:

[donnie@fedora ~]$ cat > fruit.txt
Peach
Peach
peach
apricot
Apricot
peach
Apricot
[donnie@fedora ~]$

Using uniq without any options gives you this:

[donnie@fedora ~]$ uniq fruit.txt
Peach
peach
apricot
Apricot
peach
Apricot
[donnie@fedora ~]$

This got rid of the duplicates that were identical in case. But you still have some consecutive words that are the same, except for case. Use the -i switch to make this operation case-insensitive, like this:

[donnie@fedora ~]$ uniq -i fruit.txt
Peach
apricot
peach
Apricot
[donnie@fedora ~]$

Of the two duplicate pairs, whichever word was on top was the one that stayed. In the Peach pair, the upper-case Peach was on top, so it stayed. In the Apricot pair, the lower-case apricot was on top, so it stayed...

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83
Tech Concepts
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Programming languages
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The Ultimate Linux Shell Scripting Guide
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