dotnet-installer/src/dotnet/commands/dotnet-help/HelpCommand.cs

// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System.Reflection;
using Microsoft.DotNet.Cli.Utils;

namespace Microsoft.DotNet.Tools.Help
{
    public class HelpCommand
    {
        private const string ProductLongName = ".NET Command Line Tools";
        private const string UsageText = @"Usage: dotnet [common-options] [command] [arguments]

Arguments:
  [command]     The command to execute
  [arguments]   Arguments to pass to the command

Common Options (passed before the command):
  -v|--verbose  Enable verbose output
  --version     Display .NET CLI Version Number
  --info        Display .NET CLI Info

Common Commands:
  new           Initialize a basic .NET project
  restore       Restore dependencies specified in the .NET project
  build         Builds a .NET project
  publish       Publishes a .NET project for deployment (including the runtime)
  run           Compiles and immediately executes a .NET project
  test          Executes tests in a test project
  repl          Launch an interactive session (read, eval, print, loop)
  pack          Creates a NuGet package";
        public static readonly string ProductVersion = GetProductVersion();

        private static string GetProductVersion()
        {
            var attr = typeof(HelpCommand).GetTypeInfo().Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>();
            return attr?.InformationalVersion;
        }

        public static int Run(string[] args)
        {
            if (args.Length == 0)
            {
                PrintHelp();
                return 0;
            }
            else
            {
                return Cli.Program.Main(new[] { args[0], "--help" });
            }
        }

        public static void PrintHelp()
        {
            PrintVersionHeader();
            Reporter.Output.WriteLine(UsageText);
        }

        public static void PrintVersionHeader()
        {
            var versionString = string.IsNullOrEmpty(ProductVersion) ?
                string.Empty :
                $" ({ProductVersion})";
            Reporter.Output.WriteLine(ProductLongName + versionString);
        }
    }
}