1. Introduction

1.1 Goal

The goal of this tutorial is to provide you with the essential techniques for debugging shell scripts. We'll cover different debugging tools and strategies, and how you can use them to identify, diagnose, and resolve issues in your shell scripts.

1.2 Learning Outcomes

By the end of this tutorial, you should be able to:
- Understand common shell scripting errors
- Use different debugging techniques
- Implement best practices to minimize errors

1.3 Prerequisites

This tutorial assumes that you have a basic understanding of shell scripting. Familiarity with Linux command line would also be beneficial.

2. Step-by-Step Guide

2.1 Debugging Techniques

There are several ways to debug shell scripts. Here are some common ones:

2.1.1 Echo Statements

Using echo to print variables or flow control statements can help you to understand the code flow and the values of variables at certain points.

2.1.2 The -v and -x options

Running your script with -v (verbose) will print each command to stdout before executing it. This can be helpful for understanding the flow of your script. Running your script with -x will print each command that is executed to stdout, as well as the result.

2.1.3 The set command

The set command can also be used to control the debugging output. For example, set -x will print each command that is executed to stdout, just like the -x option.

2.2 Best Practices

• Use descriptive variable and function names
• Follow a consistent code style
• Regularly use a linter to check your code

3. Code Examples

3.1 Echo Statements

#!/bin/bash

VAR="Hello World"
echo "The value of VAR is: $VAR"

3.2 The -v and -x options

#!/bin/bash -v
VAR="Hello World"
echo $VAR

#!/bin/bash -x
VAR="Hello World"
echo $VAR

3.3 The set command

#!/bin/bash

set -x
VAR="Hello World"
echo $VAR
set +x

In each of these examples, the output will include the echo command and the value of VAR.

4. Summary

In this tutorial, we've covered some common debugging techniques in shell scripting. With these techniques, you should be able to identify, diagnose, and fix issues in your shell scripts more efficiently.

5. Practice Exercises

5.1 Exercise 1

Write a shell script that prints the first 10 natural numbers, and debug it using echo statements.

5.2 Exercise 2

Write a shell script that reads a number from the user and calculates its factorial, and debug it using the set command.

5.3 Exercise 3

Write a shell script that sorts an array of numbers in ascending order, and debug it using the -v and -x options.