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

Chapter 5 - Script 1

# 5/16/2017
echo "script1 - Linux Scripting Book"

echo "Enter 'q' to quit."
while [ $rc -eq 0 ]
 echo -n "Enter a string: "
 read str
 echo "str: $str"
 if [ "$str" = "q" ] ; then

echo "End of script1"
exit 0

And here is the output when run on my system:

This is a good one to run on your system. Try several different strings, numbers, and so on. Notice how the returned string contains whitespace, special characters, and so on. You don't have to quote anything, and if you do those will be returned as well.

You can also use the read command to put a simple pause into your script. This will allow you to see the output before it scrolls off the screen. It can also be used when debugging which will be shown in Chapter 9, Debugging Scripts.

The following script shows how to create a pause when the output gets to the last line of the screen:

Chapter 5 - Script 2

# 5/16/2017
# Chapter 5 - Script 2
linecnt=1                    ...