Book Image

Linux Shell Scripting Bootcamp

By : James K Lewis
Book Image

Linux Shell Scripting Bootcamp

By: James K Lewis

Overview of this book

Linux Shell Scripting Bootcamp is all about learning the essentials of script creation, validating parameters, and checking for the existence of files and other items needed by the script. We will use scripts to explore iterative operations using loops and learn different types of loop statements, with their differences. Along with this, we will also create a numbered backup script for backup files. Further, you will get well-versed with how variables work on a Linux system and how they relate to scripts. You’ll also learn how to create and call subroutines in a script and create interactive scripts. The most important archive commands, zip and tar, are also discussed for performing backups. Later, you will dive deeper by understanding the use of wget and curl scripts and the use of checksum and file encryption in further chapters. Finally, you will learn how to debug scripts and scripting best practices that will enable you to write a great code every time! By the end of the book, you will be able to write shell scripts that can dig data from the web and process it efficiently.
Table of Contents (19 chapters)
Linux Shell Scripting Bootcamp
About the Author
About the Reviewer
Customer Feedback

Introducing the wget program

You may have already heard about or even used the wget program. It is a command line utility that can be used to download files from the Internet.

Here is a screenshot showing wget in its most simplest form:

wget options

In the output you can see that wget downloaded the index.html file from my website.

This is the default behavior of wget. The standard usage is:

  wget [options] URL

where URL stands for Uniform Resource Locator, or address of the website.

Here is just a short list of the many available options with wget:




log file, messages will be written here instead of to STDOUT


same as -o excepts it appends to the log file


output file, copy the file to this name


turn debugging on


quiet mode


verbose mode


recursive mode

Let's try another example:

The -o option was used in this case. The return code was checked and a code of 0 means no failure. There was no output because it was directed...