How do you monitor a network folder for new files?

ICSM Computer 844 18 May 2025

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Updated 18 May 2025

1 Answers

ICSM Computer 18 May 2025

To monitor a network folder for new files in C#, you can use the FileSystemWatcher class, which works on both local and network paths (e.g., \\server\share or a mapped drive).

Example: Monitor a Network Folder for New Files

using System;
using System.IO;

class Program
{
    static void Main()
    {
        string networkPath = @"\\server\sharedfolder"; // or mapped drive like "Z:\sharedfolder"

        using FileSystemWatcher watcher = new FileSystemWatcher
        {
            Path = networkPath,
            Filter = "*.*", // watch all file types
            NotifyFilter = NotifyFilters.FileName | NotifyFilters.CreationTime,
            IncludeSubdirectories = false, // true if needed
            EnableRaisingEvents = true
        };

        watcher.Created += (s, e) =>
        {
            Console.WriteLine($"New file detected: {e.FullPath}");
        };

        Console.WriteLine("Watching network folder for new files. Press Enter to exit.");
        Console.ReadLine();
    }
}

Notes

Ensure the app has read permissions on the network share.
The FileSystemWatcher depends on underlying OS file change notifications, so it generally works on SMB/CIFS shares.
Some network file systems (e.g., NFS or certain cloud-mounted drives) may not support change notifications. In that case, use polling (see below).

Alternative: Polling Fallback (if watcher fails on network)

var knownFiles = new HashSet<string>(Directory.GetFiles(networkPath));

while (true)
{
    var currentFiles = Directory.GetFiles(networkPath);
    foreach (var file in currentFiles)
    {
        if (!knownFiles.Contains(file))
        {
            Console.WriteLine("New file found: " + file);
            knownFiles.Add(file);
        }
    }

    Thread.Sleep(5000); // check every 5 seconds
}

Best Practices

Handle exceptions (e.g., access denied, path not found).
Use try/catch inside event handlers — network paths can become unavailable.
Log the event timestamp and file name for auditing.

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