using System;

using System.IO;

using System.Linq;

​

public class Program

{

    public static void Main(string[] args)

    {

        var files = new[] { "file1.dll", "file2.dll" };

        var paths = Environment.GetEnvironmentVariable("PATH").Split(';');

​

        var existsList = from file in files

                         from path in paths

                         group File.Exists($"{path}/{file}") by file into g

                         select new

                         {

                             Dll = g.Key,

                             Exists = g.Any(x => x)

                         };

        foreach (var entry in existsList)

        {

            Console.WriteLine($"dll {entry.Dll} {(entry.Exists ? "Exists" : "Does not exist")} on PATH");

        }

    }

}

​

​