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

Watching a process

There are a few more topics that we should look at in this chapter. Suppose you want to be alerted when a running process ends on your system.

Here's a script that notifies the user when the specified process ends. Note that there are other ways to do this task, this is just one approach.

Chapter 3 - Script 12

# 5/3/2017
echo "script12 - Linux Scripting Book"

if [ $# -ne 1 ] ; then
 echo "Usage: script12 process-directory"
 echo " For example: script12 /proc/20686"
 exit 255

FN=$1                        # process directory i.e. /proc/20686
while [ $rc -eq 1 ]
 if [ ! -d $FN ] ; then      # if directory is not there
  echo "Process $FN is not running or has been terminated."
  let rc=0
  sleep 1

echo "End of script12"
exit 0

To see this script in action run the following commands:

  • In a terminal, run script9

  • In another terminal run ps auxw | grep script9. The output will be something like this:

    guest1   20686  0.0  0.0 106112  1260 pts...