using System;

using System.IO;

using System.Threading;

using System.Linq;

public class Program

{

    public static void Main()

    {

​

    }

  public static void RetryMethod()

        {

      string filePath=@"C:\tmp\log.txt";

​

            while(true)

            {

                try

                {

                    var lastLine = File.ReadLines(filePath).Last();

​

​

                    if (lastLine.Contains("stringToFind"))

                    {

                        break;

                    }

                    else

                    {

                        Thread.Sleep(1000);

                    }

​

                }

                catch

                {

                    //...

                }

            }

        }

}