Program.cs

using Meziantou.Framework.Win32;
using System;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Management;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp53
{
    class Program
    {
        static void Main(string[] args) =>
            MainAsync().GetAwaiter().GetResult();

        static async Task MainAsync()
        {
            var source = new CancellationTokenSource();
            var task = LockFile("C:/temp/test.txt", source.Token);

            Console.ReadLine();
            // Meziantou.Framework.Win32.RestartManager
            using (var manager = RestartManager.CreateSession())
            {
                manager.RegisterFile("C:/temp/test.txt");

                foreach (var process in manager.GetProcessesLockingResources())
                {
                    Console.Write(process.Id);
                    Console.Write("\t");
                    Console.Write(process.ProcessName);
                    Console.Write(" ");
                    Console.WriteLine(process.GetCommandLine());
                }
            }

            Console.ReadLine();
            source.Cancel();

            await task;
        }

        static Task LockFile(string file, CancellationToken cancellationToken)
        {
            return Task.Run(
                () =>
                {
                    using (var stream = new FileStream(file, FileMode.Open, FileAccess.ReadWrite, FileShare.None))
                    {
                        cancellationToken.WaitHandle.WaitOne();
                    }
                },
                cancellationToken
            );
        }
    }
    static class ProcessExtensions
    {
        public static string GetCommandLine(this Process process)
        {
            // System.Management
            using (var searcher = new ManagementObjectSearcher("SELECT CommandLine FROM Win32_Process WHERE ProcessId = " + process.Id))
            using (var objects = searcher.Get())
            {
                return objects.Cast<ManagementBaseObject>().SingleOrDefault()?["CommandLine"]?.ToString();
            }

        }
    }
}