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Learning Linux Shell Scripting

You're reading from   Learning Linux Shell Scripting Unleash the power of shell scripts to solve real-world problems by breaking through the practice of writing tedious code

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Product type Paperback
Published in Dec 2015
Publisher
ISBN-13 9781785286216
Length 306 pages
Edition 1st 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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Toc

Table of Contents (14) 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. Working with Functions 10. Using Advanced Functionality in Scripts 11. System Startup and Customizing a Linux System 12. Pattern Matching and Regular Expressions with sed and awk Index

Understanding variables


Let's learn about creating variables in shell.

Declaring variables in Linux is very easy. We just need to use the variable name and initialize it with the required content.

$ person="Ganesh Naik"

To get the content of the variable we need to prefix $ before the variable.

For example:

$ echo person
person
$ echo $person
Ganesh Naik

The unset command can be used to delete a variable:

$ a=20
$ echo $a
$ unset a

The unset command will clear or remove the variable from shell environment as well.

$ person="Ganesh Naik"
$ echo $person
$ set

Here, the set command will show all variables declared in shell.

$ declare  -x variable=value

Here, the declare command with the –x option will make it an environmental or global variable. We will understand more about environmental variables in the next sessions.

$ set

Again here, the set command will display all variables as well as functions that have been declared.

$ env

Here, the env command will display all environmental variables...

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