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using System;
using System.IO;

class Program
{
  static void Main()
  {
    string filename = @"c:\test.txt";
    FileSystemWatcher fsw = new FileSystemWatcher(
      Path.GetDirectoryName(filename),
      Path.GetFileName(filename));
    fsw.Changed += delegate(object sender, FileSystemEventArgs e)
    {
      Console.WriteLine("modified!");
    };
    while (true)
      fsw.WaitForChanged(WatcherChangeTypes.All);
  }
}