C# program to compute MD5 hash of files specified as command-line arguments

md5.cs

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Security.Cryptography;

static class Program 
{
    static void Run(IEnumerable<string> args) 
    {
        args = from arg in args
               select arg.Trim() into arg
               where !string.IsNullOrEmpty(arg)
               select arg;

        if (!args.Any())
            throw new Exception("Missing file path.");
        
        foreach (var e in from path in args
                          select new 
                          {
                             Path = Path.GetFullPath(path),
                             Hash = BitConverter.ToString(MD5Hash(path))
                                                .ToLowerInvariant()
                                                .Replace("-", string.Empty)
                          })
        {
            Console.WriteLine(e.Hash + " " + e.Path);
        }
    }

    static byte[] MD5Hash(string path)
    {
        using (var stream = new FileStream(path, FileMode.Open,
                                                 FileAccess.Read,
                                                 FileShare.Read,
                                                 4096,
                                                 FileOptions.SequentialScan))
        {
            return MD5.Create().ComputeHash(stream);
        }
    }

    static int Main(string[] args)
    {
        try
        {
            Run(args);
            return 0;
        }
        catch (Exception e)
        {
            Console.Error.WriteLine(e.Message);
            Trace.TraceError(e.ToString());
            return Environment.ExitCode != 0 ? Environment.ExitCode : 0xbad;
        }
    }
}