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

Making a current backup of your work

And now, for another bonus the next section shows the script I used to backup my current book's chapter every 60 seconds:

Chapter 4 – Script 7

# Auto backs up the file given if it has changed
# Assumes the cbS command exists
# Checks that ../back exists
# Copies to specific USB directory
# Checks if filename.bak exists on startup, copy if it doesn't

echo "autobackup by Lewis 5/9/2017 A"
if [ $# -ne 3 ] ; then
 echo "Usage: autobackup filename USB-backup-dir delay"
 exit 255

# Create back directory if it does not exist
if [ ! -d back ] ; then
 mkdir back

FN=$1                        # filename to monitor
USBdir=$2                    # USB directory to copy to
DELAY=$3                     # how often to check

if [ ! -f $FN ] ; then       # if no filename abort
 echo "File: $FN does not exist."
 exit 5

if [ ! -f $FN.bak ] ; then
 cp $FN $FN.bak

while [ 1 ]
 cmp $FN $FN.bak
 if [ $rc -ne 0 ] ; then