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Learning Linux Shell Scripting

You're reading from   Learning Linux Shell Scripting Leverage the power of shell scripts to solve real-world problems

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Product type Paperback
Published in May 2018
Publisher Packt
ISBN-13 9781788993197
Length 332 pages
Edition 2nd Edition
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Author (1):
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Ganesh Sanjiv Naik Ganesh Sanjiv Naik
Author Profile Icon Ganesh Sanjiv Naik
Ganesh Sanjiv Naik
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Table of Contents (17) Chapters Close

Preface 1. Getting Started and Working with Shell Scripting FREE CHAPTER 2. Drilling Deep into Process Management, Job Control, and Automation 3. Using Text Processing and Filters in Your Scripts 4. Working with Commands 5. Exploring Expressions and Variables 6. Neat Tricks with Shell Scripting 7. Performing Arithmetic Operations in Shell Scripts 8. Automating Decision-Making in Scripts 9. Automating Repetitive Tasks 10. Working with Functions 11. Using Advanced Functionality in Scripts 12. System Startup and Customizing a Linux System 13. Pattern Matching and Regular Expressions with sed and awk 14. Taking Backup and Embedding Other Languages in Shell Scripts 15. Database Administration Using Shell Scripts 16. Other Books You May Enjoy

Working with environment variables

Environmental variables are inherited by any subshells or child processes, for example, HOME, PATH. Every shell Terminal has a memory area called the environment. Shell keeps all details and settings in the environment. When we start a new Terminal or shell, this environment is created every time.

We can view the environment variables with the following command:

$ env

Or we can use this:

$ printenv

The output of the $ env command is as follows:

The list of environment variables will be quite extensive. I advise you to browse through the complete list. We can change the content of any of these environment variables.

Environmental variables are defined in a Terminal or shell. They will be available in any subshells or child shells created from the current shell Terminal. You will learn about these activities in the next few sections. You have...

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