LogFilter - Simple application for filtering content from large w3c logs.

Program.cs

using System.IO;

namespace LogFilter
{
    class Program
    {
        static void Main(string[] args)
        {
            const string InputPath = @"D:\Temp\u_ex191014.log";
            const string OutputPath = @"D:\Temp\output.log";

            using var input = new StreamReader(InputPath);
            using var output = new StreamWriter(OutputPath);
            while (true)
            {
                var line = input.ReadLine();

                if (string.IsNullOrEmpty(line))
                    break;

                // comment
                if (line.StartsWith("#"))
                    continue;

                // date time s-ip cs-method cs-uri-stem cs-uri-query s-port cs-username c-ip cs(User-Agent) cs(Referer) sc-status sc-substatus sc-win32-status time-taken
                var tokens = line.Split(' ');

                // ignore these originating addresses
                if (tokens[8] == "172.18.25.1" || tokens[8] == "172.18.100.52")
                    continue;

                // status code must be 500
                if (tokens[11] != "500")
                    continue;

                // path must start with /v2
                if (!tokens[4].StartsWith("/v2"))
                    continue;

                output.WriteLine(line);
            }

        }
    }
}