How to develop a .NET Command Line Interface (CLI) Tool using the new .NET 6 technology and build your own global tools to make your work easier.

Built with

• .NET 6 Console App
• DotNet Tool & nupkg

Prerequisites

• Make sure you are running on the latest .NET 6 SDK (SDK 6.0 and above only).
• Visual Studio 2022 or Rider 2021.3.1

Create your own CLI

On this example, we will create an .NET Core CLI tool use to check current weather data for a given city, you may need to register OpenWeatherMap's API.

Then run this command to create .NET Core Console app in your computer

dotnet new console Weather.Cli

After it's done, let create a Weather Service class, the purpose of this class is to fetch the weather data from API.

public static class WeatherService
{
    const string API_KEY = "YOUR_API_KEY";
    public static async Task Run(string[] args)
    {
        var httpClient = new HttpClient()
        {
            BaseAddress = new Uri("https://api.openweathermap.org/")
        };       
        var continuesCheck = true;
        do
        {
            var city = args.AsQueryable().FirstOrDefault();
            if (city == null)
            {
                Console.Write("Enter the city: ");
                city = Console.ReadLine()!.Trim();
            }

            var response = await httpClient.GetAsync($"data/2.5/weather?q={city}&appid={API_KEY}&units=metric");
            if (response.StatusCode == HttpStatusCode.NotFound)
            {
                Console.WriteLine($"Weather not found for this city: {city}");
                continue;
            }

            var currentWeather = await response.Content.ReadFromJsonAsync<WeatherObject>();

            Console.WriteLine($"Current weather for city: {city}");           
            if (currentWeather != null)
            {
                Console.WriteLine($"City: {currentWeather.Name}");
                Console.WriteLine($"Country: {currentWeather.Sys?.Country}");
                Console.WriteLine($"Weather: {currentWeather.Weather![0].Description}");
                Console.WriteLine($"Temperature: {currentWeather.Main!.Temp}°C");
                Console.WriteLine($"Humidity: {currentWeather.Main!.Humidity}%");
                Console.WriteLine($"Pressure: {currentWeather.Main!.Pressure}hPa");
                Console.WriteLine($"Wind: {currentWeather.Wind!.Speed}m/s, {currentWeather!.Wind!.Deg}°");
                Console.WriteLine($"Clouds: {currentWeather.Clouds!.All}%");
            }
            
            Console.WriteLine($"Continues to check the weather for another city? (Y/N)");
            
            if (Console.ReadLine()!.Trim() != "Y")  continuesCheck = false;
            
        } while (continuesCheck);
        
    }
}

Let make sure you can build and run the project,

Then we can able to config this console app as the nupkg tool by adding more these lines to Weather.Cli.csproj file.

<PackAsTool>true</PackAsTool>
<ToolCommandName>weather</ToolCommandName>
<PackageOutputPath>./nupkg</PackageOutputPath>

With this <ConsoleWindows text={"weather"} />, we configured the CLI will be execute by typing weather in the command line.

Build the nupkg

dotnet pack

then install this nupkg as global tools with the local ./nupkg source by using this command line

dotnet tool install --global -add-source ./nupkg weather.cli

Finally, we can execute this CLI tool anywhere by enter weather in command line