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

Using functions within Perl

As with all languages, the ability to encapsulate a code within functions can make the code more readable and ultimately results in easier to manage codes, with less number of lines. Unlike bash, the functions in Perl can be defined after they are referenced in the code and we often choose to define the functions at the end of the script.

Prompt for user input

We have seen the use of command-line arguments in Perl; now, let's take a look at prompting for user input. This becomes a great way to encapsulate the code to execute and store the prompt within a function. First of all, we will look at a simple script that prompts for the username and then we will modify it to include the function. We will create the $HOME/bin/ file to read, as shown in the following code example:

my $name;
print("Enter your name: ");
chomp( $name = <STDIN> );
print("Hello $name\n");

In line 2, we have declared the variable using my. The keyword my defines the...