Any computer that has Linux OS installed in it will be sufficient for learning all the topics discussed in this book. For the first edition, we used Ubuntu Linux distribution. For this second edition, we have used CentOS Linux distribution. I have personally tested all the commands and scripts in Ubuntu 16.04, as well as in the CentOS 7.0 distribution.

During the course, if you find that any particular utility is not installed in Ubuntu or any Debian-based distribution, then enter the following command to install that utility:

$ sudo apt-get update
$ sudo apt-get install package-name

A good internet connection should be available for the preceding commands to run.

In CentOS or any other rpm-based distribution, enter the following commands:

$ sudo yum update
$ sudo yum install package-name

If the internet is connected, then using these commands you can install any command or utility that is not already installed.

You can download the example code files for this book from your account at www.packtpub.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packtpub.com.
2. Select the SUPPORT tab.
3. Click on Code Downloads & Errata.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Learning-Linux-Shell-Scripting-Second-Edition. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalogue of books and videos available at https://github.com/PacktPublishing/. Check them out!

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Mount the downloaded WebStorm-10*.dmg disk image file as another disk in your system."

A block of code is set as follows:

#!/bin/bash 
# This is comment line 
echo "Hello World" 
ls 
date 

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

#!/bin/bash 
# This is comment line 
echo "Hello World" 
ls 
date 

Any command-line input or output is written as follows:

 $ bash hello.sh

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Select System info from the Administration panel."