示例：找出某程序的PID

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace Test3
{
    class Program
    {
        static void Main(string[] args)
        {
            System.Diagnostics.Process process = new System.Diagnostics.Process();
            process.StartInfo.FileName = "netstat";
            process.StartInfo.Arguments = "-a -n -o -p TCP";
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.RedirectStandardOutput = true;
            //process.StartInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
            //process.StartInfo.CreateNoWindow = true;
            process.Start();

            string output = process.StandardOutput.ReadToEnd();
            string[] lines = output.Split('\n');

            process.WaitForExit();

            Console.WriteLine(output);

            foreach (string line in lines)
            {
                string[] tokens = Regex.Split(line, "\\s+");//按不可见字符分割
                if (tokens.Length > 4)
                {
                    int test = -1;
                    int.TryParse(tokens[5], out test);

                    if (test > 1023) //排除系统进程
                    {
                        try
                        {
                            var p = System.Diagnostics.Process.GetProcessById(test);
                            if (p.ProcessName == "Unity")
                            {
                                Console.WriteLine("Unity PID: {0}", test);
                                break;
                            }
                        }
                        catch
                        {

                        }
                    }
                }
            }
            Console.ReadKey();
        }
    }
}

运行测试