How to monitor a text file and parse new lines?

Question

I wondering if there is a way to monitor a .txt file without locking it and have the newly appended lines parsed in order to be sent to a database.

I know FileSystemWatcher will monitor the txt file without locking it and notify me if a change has occurred. The problem is that it does not tell the lines of data that has been appended. All of the examples I have looked at exclude the part of displaying newly appended lines or doing any processing of the new data. My program has the following structure:

static void Main(string[] args)
{
      
  //string line;

  //createWatcher (FileSystemWatcher)
  foreach (string line in getLines(@"C://Documents/log.txt"))
  {
    string teststring = line;         
    string[] parts = line.Split(' ', ',', '-', '>', '[', ']');
    StringBuilder builder = new StringBuilder();
            
    foreach (string h in parts)
    {
      builder.Append(h).Append(" ");
    }

    string result = builder.ToString();
    string cleanedString = System.Text.RegularExpressions.Regex.Replace(result, @"\s+", " ");
    string trimString = cleanedString.Trim();
    trimString = trimString.Remove(trimString.Length - 7);

    //Console.WriteLine(trimString);

    //Process new lines (parse/split)
    //Connect and send to database
  }
}

So my objective is to monitor a .txt file without locking it.

1. Read this file for existing data, and wait for appended data.
2. I then want to parse this data and send it to a database.

Does anyone know how to best approach this? or have a good tutorial?

Answer 1

Your best bet is for the code fired off of the file system watcher to keep track of the Position in the stream that's reading the file. Here's some pseudocode:

if(no stored position)
  start at beginning of file
else
{
  streamOfFile.Seek(storedPosition)
  read until end of file
  store stream.Postition
}