FileSystemWatcher: The Native File Spy You Didn't Know You Had

Your app can watch a file like a nosy neighbor peeking through blinds - no polling loop required.

FileSystemWatcher is a built-in .NET class that monitors a folder and fires events when files get created, changed, renamed, or deleted. No need to loop and check timestamps every second like it’s 1999.

It’s been in .NET since version 1.0, originally built so apps could react instantly to log files, config changes, or dropped files in a folder without hammering the disk.

watcher.Changed += (s, e) =>Console.WriteLine($”Detected change: {
  e.ChangeType
}
on {
  e.Name
}”); // <<< fires when the watched file changes
watcher.EnableRaisingEvents = true;
File.WriteAllText(filePath, “first write”);
Thread.Sleep(500);
File.AppendAllText(filePath, “ - update ! ”);

Microsoft built you a file system spy. Use it responsibly.

Try it yourself (no setup required): https://dotnetfiddle.net/TX4OiP