Create StreamWriter from FileStream
using System; using System.IO; public class SWBuff { public static void Main(String[] args) { string logFile = "a.log"; string fileName = "a.log"; string textToAdd = "asdf"; FileStream fs = new FileStream(fileName, FileMode.CreateNew, FileAccess.Write, FileShare.None); StreamWriter swFromFileStream = new StreamWriter(fs); swFromFileStream.Write(textToAdd); swFromFileStream.Flush(); swFromFileStream.Close(); } }