Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Overview of this book

The shell remains one of the most powerful tools on a computer system — yet a large number of users are unaware of how much one can accomplish with it. Using a combination of simple commands, we will see how to solve complex problems in day to day computer usage.Linux Shell Scripting Cookbook, Second Edition will take you through useful real-world recipes designed to make your daily life easy when working with the shell. The book shows the reader how to effectively use the shell to accomplish complex tasks with ease.The book discusses basics of using the shell, general commands and proceeds to show the reader how to use them to perform complex tasks with ease.Starting with the basics of the shell, we will learn simple commands with their usages allowing us to perform operations on files of different kind. The book then proceeds to explain text processing, web interaction and concludes with backups, monitoring and other sysadmin tasks.Linux Shell Scripting Cookbook, Second Edition serves as an excellent guide to solving day to day problems using the shell and few powerful commands together to create solutions.
Table of Contents (16 chapters)
Linux Shell Scripting Cookbook
About the Authors
About the Reviewers

Tracking changes to a website

Tracking changes to a website is helpful to web developers and users. Checking a website manually in intervals is really hard and impractical. Hence, we can write a change tracker running at repeated intervals. When a change occurs, it can play an audio or send some other notification. Let us see how to write a basic tracker for the website changes.

Getting ready

Tracking changes in terms of Bash scripting means fetching websites at different times and taking the difference by using the diff command. We can use curl and diff to do this.

How to do it...

Let's write a Bash script by combining different commands, to track changes in a web page:

#Desc: Script to track changes to webpage

if [ $# -ne 1 ];
  echo -e "$Usage: $0 URL\n"
  exit 1;

# Not first time

if [ ! -e "last.html" ];
  # Set it is first time run

curl --silent $1 -o recent.html

if [ $first_time -ne 1 ];