cicatrix

class Program
    {
        static void Main(string[] args)
        {
            string filename = "C:\\1.txt";
            byte[] filebytes = File.ReadAllBytes(filename);
            using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Write, FileShare.None))
            {
                fs.Seek(0, SeekOrigin.End);
                fs.Write(filebytes, 0, filebytes.Length);
            } // using fs
        } // Main
    } // class Program