Creating Interactive Scripts | Mastering Linux Shell Scripting

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Mastering Linux Shell Scripting

By : Andrew Mallett

4.3 (10)

Mastering Linux Shell Scripting

4.3 (10)

By: Andrew Mallett

Overview of this book

Shell scripting is a quick method to prototype a complex application or a problem by automating tasks when working on Linux-based systems. Using both simple one-line commands and command sequences complex problems can be solved with ease, from text processing to backing up sysadmin tools. In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Get to grips with the fundamentals of creating and running a script in normal mode, and in debug mode. Learn about various conditional statements' code snippets, and realize the power of repetition and loops in your shell script. Implement functions and edit files using the Stream Editor, script in Perl, program in Python – as well as complete coverage of other scripting languages to ensure you can choose the best tool for your project.

Mastering Linux Shell Scripting

Mastering Linux Shell Scripting

Credits

Credits

About the Author

About the Author

About the Reviewer

About the Reviewer

www.PacktPub.com

www.PacktPub.com

Preface

Preface

Free Chapter

What and Why of Scripting with Bash

What and Why of Scripting with Bash

Bash vulnerabilities

The bash command hierarchy

Preparing text editors for scripting

Creating and executing scripts

Debugging your scripts

Summary

Creating Interactive Scripts

Creating Interactive Scripts

Using echo with options

Basic script using read

Script comments

Enhancing scripts with read prompts

Limiting the number of entered characters

Controlling the visibility of entered text

Enhancing learning with simple scripts

Summary

Conditions Attached

Conditions Attached

Simple decision paths using command-line lists

Verifying user input with lists

Using the test shell builtin

Creating conditional statements using if

Extending if with else

More conditions with elif

Using case statements

Script – building a front-end with grep

Summary

Creating Code Snippets

Creating Code Snippets

Abbreviations

Using code snippets

Summary

Alternative Syntax

Alternative Syntax

Recapping test

Providing parameter defaults

When in doubt – Quote!

Advanced test using [[

Arithmetic operations using ((

Summary

Iterating with Loops

Iterating with Loops

For loops

Controlling the loop

Reading input from files

Creating operator menus

Summary

Creating Building Blocks with Functions

Creating Building Blocks with Functions

Introducing functions

Passing parameters to functions

Returning values from functions

Using functions in menus

Summary

Introducing sed

Introducing sed

Using grep to display text

Using regular expressions

Understanding the basics of sed

Summary

Automating Apache Virtual Hosts

Automating Apache Virtual Hosts

Apache name-based Virtual Hosts

Automating Virtual Host creation

Summary

Awk Fundamentals

Awk Fundamentals

The history behind awk

Displaying and filtering content from files

Formatting output

Further filtering to display users by UID

Awk control files

Summary

Summarizing Logs with Awk

Summarizing Logs with Awk

The HTTPD log file format

Displaying data from web logs

Displaying the highest ranking IP address

Displaying the browser data

Working with e-mail logs

Summary

A Better lastlog with Awk

A Better lastlog with Awk

Using awk ranges to exclude data

Conditions based on the number of fields

Manipulating the awk record separator to report on XML data

Summary

Using Perl as a Bash Scripting Alternative

Using Perl as a Bash Scripting Alternative

What is Perl?

Hello World

Perl arrays

Conditional statements in Perl

Using functions within Perl

Summary

Using Python as a Bash Scripting Alternative

Using Python as a Bash Scripting Alternative

What is Python?

Saying Hello World the Python way

Pythonic arguments

Significant whitespace

Reading user input

Summary

Index

Index

Chapter 2. Creating Interactive Scripts

In Chapter 1, What and Why of Scripting with Bash, of this book we learned how to create a script and use some of its basics elements. These include optional parameters that we can pass through to the script when it is executed. In this chapter, we will extend this by using the read shell built-in command to allow for interactive scripts. Interactive scripts are scripts that prompt for information during the script execution. In doing so, we will cover the following topics:

Using echo with options
Basic script using read
Adding comments
Enhancing read scripts with prompts
Limiting the number of entered characters
Control the visibility of the entered text
Simple scripts to enforce our learning

CONTINUE READING

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Tech Concepts

36

Programming languages

73

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