Belmansour / Brady Building CLI Applications with C# and .NET

A step-by-step guide to developing cross-platform CLI apps—from coding and testing to deployment
1. Auflage 2025
ISBN: 978-1-83588-275-7
Verlag: De Gruyter
Format: EPUB
Kopierschutz: 0 - No protection

E-Book, Englisch, 306 Seiten

Developers and system administrators often face challenges like inefficient workflows, complex system operations, and the growing demand for robust automation tools. CLI applications provide a powerful solution by enhancing flexibility, efficiency, and productivity in various environments. This book will guide you through mastering the development of robust command-line tools using .NET.
Written by a Microsoft Azure MVP, the book's hands-on approach ensures practical experience with real-world projects. You'll start with an overview of foundational principles, essential concepts, and best practices for CLI application development. From there, you'll advance to creating interactive interfaces, integrating with external APIs and services, and implementing security measures to safeguard your applications. Each chapter will build progressively from basic to advanced topics.
Beyond development, you'll learn how to enhance application quality through testing, package for efficient distribution, and deploy effectively. The book also teaches strategies to optimize performance to ensure your applications run efficiently under heavy usage.
By the end of this book, you'll have gained a deep understanding of CLI application development with .NET to build modular, extensible, and easy-to-maintain applications.

Autoren/Hrsg.

Belmansour, Tidjani

Brady, Damian

Weitere Mitwirkende

Brady, Damian

Fachgebiete

• Mathematik | Informatik EDV | Informatik Programmierung | Softwareentwicklung Software Engineering

Leseproben

Table of Contents

Preface

Free Benefits with Your Book

Part 1: Getting Started with CLI Applications

1

Introduction to CLI Applications

A day in the life of an IT professional

Why care about CLI applications?

To CLI or not to CLI?

CLI applications as the building block for creating workstation profiles

Even heavy graphical applications have a CLI tool!

Even ChatGPT has a CLI!

Summary

2

Setting Up the Development Environment

Technical requirements

Installing Visual Studio Code

Installing the required extensions

Installing the .NET SDK

Installing and configuring Git

Summary

Your turn!

3

Basic Concepts of Console Applications in .NET

Technical requirements

Creating (and executing) a simple console application

Working with the System.Console class

Useful properties

Useful methods

Useful event

One more thing

Summary

Your turn!

Part 2: Foundations of Building CLI Applications

4

Command-Line Parsing

Technical requirements

Creating the console application

Parsing the arguments of a console application

From console to CLI – parsing the arguments using an existing library

Adding the root command

Adding the link command

About commands

Do all commands need to have a handler method?

Adding options to the link command

What other types of options can we use?

Getting help

Getting the application’s version number

Summary

Your turn!

Task #1 – Delete an existing bookmark

Task #2 – Update an existing bookmark

Task #3 – List all existing bookmarks

5

Input/Output and File Handling

Technical requirements

Controlling input values for an option

Required versus non-required options

What about arguments?

Setting a default value for an option

Controlling the allowed values for an option

Validating input values

Adding multiple elements in one go

Working with files passed in as options values

Summary

Your turn!

Task #1 – validating the format and the ability to access the input file

Task #2 – merging existing links from the input file

6

Error Handling and Logging

Technical requirements

Handling errors in CLI applications

Handling exceptions

Handling errors doesn’t necessarily mean handling exceptions

Handling program termination

Logging in CLI applications

Why JSON?

Why Serilog?

Accessing IServiceCollection

Adding Serilog to IServiceCollection

Adding (and configuring) the required Serilog sinks

Configuring sinks in appsettings.json

Let’s log something!

Closing and gracefully disposing of Serilog

Summary

Your turn!

Task #1 – Handling errors for the Import command

Task #2 – Logging errors to a file

Part 3: Advanced Topics in CLI Application Development

7

Interactive CLI Applications

Technical requirements

Building interactive command-line applications

Adding a FIGlet

Designing user-friendly CLI applications

Enhancing text display using markup

Offering choices to the user using selection prompts

Showing live progress of the export command

Displaying bookmarks in a tree view

To be or not to be interactive?

Summary

Your turn!

Task 1 – present a bookmark in a user-friendly way

Task 2 – change the category of a bookmark interactively

8

Building Modular and Extensible CLI Applications

Technical requirements

Step 1 – building a code map of the application

Using the Help menu to build the code map

Step 2 – deciding where to start

Step 3 – designing the project structure

Step 4 – refactoring the export command

Step 5 – applying the dependency inversion principle

Step 6 – refactoring the Program class

Step 7 – running the program

Taking refactoring to new heights

Updating the project structure

Summary

Your turn!

Task #1 – refactor the remaining commands

9

Working with External APIs and Services

Technical requirements

Why consume external APIs?

How to consume an external API

Benefits of using IHttpClientFactory

Bookmarkr: your bookmarks, anywhere!

The sync command

Registering the sync command

Running the program

Reducing the coupling between our application and the external dependency

About the Service Agent pattern

Implementing the Service Agent pattern

Rerunning the program

Summary

Your turn!

Task #1 – adding SQLite as a data store

Task #2 – retrieving the web page name based on its URL

Part 4: Testing and Deployment

10

Testing CLI Applications

Technical requirements

Why is testing so important?

Types of tests

About usability tests

The pyramid of (software) testing

What should we test?

What not to test

Testing is a safety net

When should we run tests?

Adding a test project to Bookmarkr

Structuring the test project

Code artifacts that should not be tested

Writing effective tests

Running our tests

Mocking external dependencies

The role of mocking

How to mock an external dependency

Mocking the BookmarkService service

Using the mock version of the BookmarkService service

Changes to the code must be made!

Going back to implementing the test cases

Internals visibility

Centralizing test initialization

How to hunt a bug

Summary

Your turn!

Task #1 – Write the required unit tests for the remaining functionalities

Task #2 – Write integration tests for the sync command

11

Packaging and Deployment

Technical requirements

A bit of terminology

Packaging and distribution options for CLI applications

Packaging and distributing a CLI application

Option #1 – as a .NET tool

Option #2 – as a Docker container

Option #3 – as a WinGet package

Managing versions of the application

Semantic versioning primer

Managing versions of a .NET tool

Managing versions of a Docker container

Managing versions of a WinGet package

Summary

Your turn!

Task #1 – allowing Linux users to install Bookmarkr using apt-get

Task #2 – allowing macOS users to install Bookmarkr using Homebrew

Part 5: Advanced Techniques and Best Practices

12

Performance Optimization and Tuning

Technical requirements

Performance optimization areas

Instrumenting .NET applications

Hot spots versus hot paths

Identifying the application’s hot spots and hot paths

Profiling Bookmarkr with BenchmarkDotNet

Monitoring BookmarkrSyncr with Azure Application Insights

Common performance optimization techniques

Optimizing Bookmarkr’s performance

Summary

Your turn!

Task #1 – Write more...

Über Autor(innen)

Belmansour Tidjani :

Tidjani Belmansour is an expert in developing and architecting solutions on the Microsoft Azure platform, particularly in.NET, with over 21 years of experience. His passion for development began early—he wrote his first program in QuickBasic at the age of eight and has never stopped since. He is currently the Director of the Azure Centre of Excellence at Cofomo, where he collaborates with organizations of all sizes, across both public and private sectors, and on projects around the globe. Since 2019, Tidjani has been recognized as a Microsoft Azure MVP. He is also the co-host of the Azure Quebec Community, a trainer, a blogger, and an international speaker. Tidjani holds a BSc in Computer Science and a Ph.D. in Engineering.