How to remove computer and process names and process ids from syslog

Question

Debian syslog contains repeating infomation like:

Dec 25 09:43:28 uvn-76-202 Eeva[7192]:          at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
Dec 25 09:43:28 uvn-76-202 Eeva[7192]:          at Program.<>c.<<Main>b__3_6>d.MoveNext() in C:\raamat\eevaweb\Store\Program.cs:line 979
Dec 25 09:43:28 uvn-76-202 Eeva[7192]:       
Dec 25 09:45:01 uvn-76-202 CRON[18528]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Dec 25 09:54:14 uvn-76-202 systemd[1]: Created slice User Slice of UID 0.

How to remove server name, process name, process id and spaces so that output is

Dec 25 09:43:28 at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
Dec 25 09:43:28 at Program.<>c.<<Main>b__3_6>d.MoveNext() in C:\raamat\eevaweb\Store\Program.cs:line 979
Dec 25 09:45:01 (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Dec 25 09:54:14 Created slice User Slice of UID 0.

Tried to use in ASP.NET 9 MVC controller

  StribBuilder sb = new();
  using StreamReader reader = new("/var/log/syslog");
  string line;
  while ((line = await reader.ReadLineAsync()) != null)
  {
    line = StrTran(line, "uvn-76-202 Eeva", "");
    line = StrTran(line, "         "), "");
    sb.AppendLine(line);
  }

static string StrTran(string cSearchIn, string cSearchFor, string cReplaceWith)
{
  StringBuilder sb = new(cSearchIn);
  return sb.Replace(cSearchFor, cReplaceWith).ToString();
}

but this removes only part of unnessecary information.

Answer 1

using System;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

public class LogProcessor
{
public static async Task<string> ProcessLogAsync(string logPath)
{
    StringBuilder sb = new();
    using StreamReader reader = new(logPath);

    string line;
    while ((line = await reader.ReadLineAsync()) != null)
    {
        // Use regex to remove the server name, process name, and process 
ID.
        line = Regex.Replace(line, @"\buvn-76-202\b.*?\[\d+\]:\s*", "");

        // Remove leading spaces (if any).
        line = line.TrimStart();

        sb.AppendLine(line);
    }

    return sb.ToString();
    }
}


class Program
{
public static async Task Main(string[] args)
{
    string logPath = "/var/log/syslog";
    string processedLogs = await LogProcessor.ProcessLogAsync(logPath);
    Console.WriteLine(processedLogs);
    }
}