Attach Selenium to an existing instance of Chrome in Windows or Linux

Program.cs

using System;
using OpenQA.Selenium.Chrome;
using System.Diagnostics;

namespace selenium
{
    class Program
    {
        static void Main(string[] args)
        {
            // Windows
            // string programPath = @"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe";
            // string dataDir = @"C:\\Temp"; // Windows

            // Linux
            string programPath = "/usr/bin/google-chrome";
            string dataDir = "/tmp";

            string port = "9222";
            string url = @"http:\\www.reddit.com";

            Process proc = new Process();
            proc.StartInfo.FileName = programPath;
            proc.StartInfo.Arguments = $@"{url} --new-window --remote-debugging-port={port} --user-data-dir={dataDir}";
            proc.Start();

            // Attach to Chrome
            ChromeOptions options = new ChromeOptions();
            options.DebuggerAddress = "127.0.0.1:9222";
            ChromeDriver driver = new ChromeDriver(options);

            driver.Navigate().GoToUrl(@"http:\\www.reddit.com");
            Console.ReadLine();
        }
    }
}