Batch help

[CeeBee]

Would be extremely difficult in a batch file.

This could be easily done in a small program. Here is a sample in C#
I've actually adapted one of my programs on the fly so it's not guaranteed to be typo-free...

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace FixFile
{
  class Program
  {
    static void Main(string[] args)
    {
      if (args.Length != 4)
      {
        Console.Write("Invalid parameters count " + args.Length.ToString() + ", expected 4");
        return;
      }

      string sInputFile;
      string sOutputFile;
      string sSearchString;
      string sCommentString;
      sInputFile = args[0];
      sOutputFile = args[1];
      sSearchString = args[2];
      sCommentString = args[3];

      TextReader reader;
      TextWriter writer;
      string sInputLine;
      string sOutputLine;

      try
      {
         writer=new StreamWriter(sOutputFile, false);
      }
      catch(Exception ex)
      {
        Console.WriteLine(ex.Message);
        return;
      }

      try
      {
        reader=new StreamReader(sInputFile);
      }
      catch(Exception ex)
      {
        Console.WriteLine(ex.Message);
        return;
      }

      while ((sInputLine = reader.ReadLine()) != null)
      {
        sOutputLine = sInputLine.Replace(sSearchString, sCommentString+sSearchString);
        writer.WriteLine(sOutputLine);
      }
      writer.Flush();
      writer.Close();
      reader.Close();
      Console.WriteLine("Program execution completed.");
    }
  }
}

Usage: FIXFILE.EXE source.txt destination.txt "search this string" "REM "