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

Getting started

You will always be able to create these scripts under a guest account, and most will run from there. It will be clearly stated when root access is needed to run a particular script.

The book will assume that the user has put a (.) at the beginning of the path for that account. If not, to run a script prepend ./ to the filename. For example:

 $ ./runme

The scripts will be made executable using the chmod command.

It is suggested that the user create a directory under his guest account specifically for the examples in this book. For example, something like this works well:

$ /home/guest1/LinuxScriptingBook/chapters/chap1

Of course, feel free to use whatever works best for you.

Following the general format of a bash script the very first line will contain this and nothing else:


Note that in every other case text following the # sign is treated as comments.

For example,

# This entire line is a comment

chmod 755 filename   # This text after the # is a comment

Use comments however you deem appropriate. Some people comment every line, some don't comment anything. I try to strike a balance somewhere in the middle of those two extremes.

Using a good text editor

I have found that most people are comfortable using vi to create and edit text documents under a UNIX/Linux environment. This is fine as vi is a very dependable application. I would suggest not using any type of word processing program, even if it claims to have a code development option. These programs might still put invisible control characters in the file which will probably cause the script to fail. This can take hours or even days to figure out unless you are good at looking at binary files.

Also, in my opinion, if you plan to do a lot of script and/or code development I suggest looking at some other text editor other than vi. You will almost certainly become more productive.