Program.cs

using System;
using System.Diagnostics;
using Gapotchenko.FX.Diagnostics;
using Newtonsoft.Json;

namespace GetProcessEnv
{
    internal static class Program
    {
        public static void Main(string[] args)
        {
            var process = Process.GetProcessById(int.Parse(args[0]));
            var env = process.ReadEnvironmentVariables();
            Console.WriteLine(JsonConvert.SerializeObject(env));
        }
    }
}