Book Image

Learning Linux Shell Scripting

By : Ganesh Sanjiv Naik
Book Image

Learning Linux Shell Scripting

By: Ganesh Sanjiv Naik

Overview of this book

Linux is the one of the most powerful and universally adopted OSes. Shell is a program that gives the user direct interaction with the operating system. Scripts are collections of commands that are stored in a file. The shell can read this file and act on the commands as if they were typed on the keyboard. Shell scripting is used to automate day-to-day administration, and for testing or product development tasks. This book covers Bash, GNU Bourne Again SHell, preparing you to work in the exciting world of Linux shell scripting. We start with an introduction to the Shell environment and explain basic commands used in Shell. Next we move on to check, kill, and control the execution of processes in Linux OS. Further, we teach you about the filter tools available in Linux and explain standard output and standard errors devices. Then we will ensure you understand Shell’s interpretation of commands and get a firmer grasp so you use them in practice. Next, you’ll experience some real-world essentials such as debugging and perform Shell arithmetic fluently. Then you’ll take a step ahead and learn new and advanced topics in Shell scripting, such as starting up a system and customizing a Linux system. Finally, you’ll get to understand the capabilities of scripting and learn about Grep, Stream Editor, and Awk.
Table of Contents (20 chapters)
Learning Linux Shell Scripting
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Creating dialog boxes with the dialog utility


The dialog utility is used to create a basic level graphical user interface. We can use this in Shell script to create very useful programs.

To install the dialog utility in Debian or Ubuntu Linux, enter following command:

$ sudo apt-get update
$ sudo apt-get install l dialog

Similarly, enter the following command to install the utility dialog in CentOS or Red Hat Linux:

$ sudo yum install dialog

The typical syntax of the dialog command is as follows:

$ dialog --common-options --boxType "Text" Height Width \
                                  --box-specific-option

The common-options utility is used to set the background color, title, and so on in dialog boxes.

The option details are as follows:

  • Text: The caption or contents of the box

  • Height: The height of the dialog box

  • Width: The width of the dialog box

Creating a message box (msgbox)

To create a simple message box, we can use the following command:

$ dialog --msgbox "This is a message." 10 50

Creating...