Book Image

Mastering Linux Shell Scripting

By : Andrew Mallett
Book Image

Mastering Linux Shell Scripting

By: Andrew Mallett

Overview of this book

Shell scripting is a quick method to prototype a complex application or a problem by automating tasks when working on Linux-based systems. Using both simple one-line commands and command sequences complex problems can be solved with ease, from text processing to backing up sysadmin tools. In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Get to grips with the fundamentals of creating and running a script in normal mode, and in debug mode. Learn about various conditional statements' code snippets, and realize the power of repetition and loops in your shell script. Implement functions and edit files using the Stream Editor, script in Perl, program in Python – as well as complete coverage of other scripting languages to ensure you can choose the best tool for your project.
Table of Contents (21 chapters)
Mastering Linux Shell Scripting
About the Author
About the Reviewer

Reading user input

If we want the welcome message to greet us by name no matter whether we supply the argument to the script or not, we can add in a prompt to capture the data while the script is running. Python makes this simple and easy to implement. We can see from the edited file shown in the screenshot that follows how this is achieved:

We make use of a new variable in the script that we set in the main block initially, to be an empty string. Set it here to make the variable available to the complete script and all code blocks.

The input function in Python 3 or raw_input can be used in Python 2 to gain user input. We store that input in the name variable. If we have supplied an argument we pick it up on the code in the else block and set the name variable to the first supplied argument. It is this that is used in the print statement back in the main block.

Using Python to write to files

To add some variety to this chapter, we will now look at printing this data to a file. Again using Python...