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


Now let's look at the curl program as it is somewhat similar to wget. One of the main differences between wget and curl is how they handle the output.

The wget program by default displays some progress information on the screen and then downloads the index.html file. In contrast, curl normally displays the file itself on the screen.

Here is an example of curl running on my system using my favorite website (screenshot shortened to save space):

Another way to get the output into a file is by using redirection like this:

You will notice that when redirected to a file the transfer progress is displayed on the screen. Also note that any error output goes into the file if redirected and not the screen.

curl options

Here is a very brief list of the options available in curl:

Curl options



Output filename


Silent mode. Shows nothing, not even errors


Show errors if in silent mode


Verbose, useful for debugging

There are many other options to curl, as well as...