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This is a fork of Microsoft.Extensions.CommandLineUtils, which is no longer under active development. This fork, on the other hand, will continue to make improvements, release updates, and accept contributions.

The roadmap for this project is pinned to the top of the issue list.


Install the NuGet package into your project.

PM> Install-Package McMaster.Extensions.CommandLineUtils
$ dotnet add package McMaster.Extensions.CommandLineUtils


See documentation for API reference, samples, and tutorials. See docs/samples/ for more examples, such as:

CommandLineApplication is the main entry point for most console apps parsing. There are two primary ways to use this API, using the builder pattern and attributes.

Attribute API

using System;
using McMaster.Extensions.CommandLineUtils;

public class Program
    public static int Main(string[] args)
        => CommandLineApplication.Execute<Program>(args);

    [Option(Description = "The subject")]
    public string Subject { get; }

    [Option(ShortName = "n")]
    public int Count { get; }

    private void OnExecute()
        var subject = Subject ?? "world";
        for (var i = 0; i < Count; i++)
            Console.WriteLine($"Hello {subject}!");

Builder API

using System;
using McMaster.Extensions.CommandLineUtils;

public class Program
    public static int Main(string[] args)
        var app = new CommandLineApplication();

        var optionSubject = app.Option("-s|--subject <SUBJECT>", "The subject", CommandOptionType.SingleValue);
        var optionRepeat = app.Option<int>("-n|--count <N>", "Repeat", CommandOptionType.SingleValue);

        app.OnExecute(() =>
            var subject = optionSubject.HasValue()
                ? optionSubject.Value()
                : "world";

            var count = optionRepeat.HasValue() ? optionRepeat.ParsedValue : 1;
            for (var i = 0; i < count; i++)
                Console.WriteLine($"Hello {subject}!");
            return 0;

        return app.Execute(args);


The library also includes other utilities for interaction with the console. These include:

  • ArgumentEscaper - use to escape arguments when starting a new command line process.
     var args = new [] { "Arg1", "arg with space", "args ' with \" quotes" };
     Process.Start("echo", ArgumentEscaper.EscapeAndConcatenate(args));
  • Prompt - for getting feedback from users. A few examples:
    // allows y/n responses
    Prompt.GetYesNo("Do you want to proceed?");
    // masks input as '*'
    Prompt.GetPassword("Password: ");
  • DotNetExe - finds the path to the dotnet.exe file used to start a .NET Core process
    Process.Start(DotNetExe.FullPathOrDefault(), "run");

And more! See the documentation for more API, such as IConsole, IReporter, and others.

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