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

Automatic backups

Now for a bit of free programming advice, making automatic backups of files was mentioned in Chapter 4, Creating and Calling Subroutines. I strongly suggest you use something like this when you are writing anything that is even slightly complicated. There is nothing more frustrating than to be working on your program or script and have it going pretty well, only to make a few changes and have it fail in some bizarre fashion. You had it working a few minutes ago and then wham! It has a fault and you can't figure out what change caused it. If you don't have a numbered backup you could literally spend hours (maybe days) trying to find the bug. I have seen people spend hours backing out every change until the problem was found. Yes, I have done it too.

Obviously if you have a numbered backup you can simply go back and find the latest one that doesn't have the fault. You can then diff the two versions and probably find the error really fast. Without a numbered backup, well you...