I'm writing a tool that's going to be check the health of workstations across a network, and will fix according to the issues it finds. I want to create a log file as the app is running through its tasks / checks on each machine. I just want to get this working on a single machine for now, but in time it will be scanning 100+ machines in one go (Threaded out).
What is the best way to create a log file?
I was thinking of using a List<string> to build up the log file in memory and then output it to a file once it had finished.
I'm just thinking there may be a better way of doing this?
You might want to use the Event Log ! Here's how to access it from C# http://support.microsoft.com/kb/307024/en
But whatever is the method that you will use, I'd recommend to output to a file every time something is appended to the log rather than when your process exits, so you won't lose data in the case of crash or if your process is killed.
I found the SimpleLogger from heiswayi on GitHub good.
Instead of using log4net which is an external library I have created my own simple class, highly customizable and easy to use (edit YOURNAMESPACEHERE with the namespace that you need).
CONSOLE APP
using System;
using System.IO;
namespace YOURNAMESPACEHERE
{
enum LogEvent
{
Info = 0,
Success = 1,
Warning = 2,
Error = 3
}
internal static class Log
{
private static readonly string LogSession = DateTime.Now.ToLocalTime().ToString("ddMMyyyy_HHmmss");
private static readonly string LogPath = AppDomain.CurrentDomain.BaseDirectory + "logs";
internal static void Write(LogEvent Level, string Message, bool ShowConsole = true, bool WritelogFile = true)
{
string Event = string.Empty;
ConsoleColor ColorEvent = Console.ForegroundColor;
switch (Level)
{
case LogEvent.Info:
Event = "INFO";
ColorEvent = ConsoleColor.White;
break;
case LogEvent.Success:
Event = "SUCCESS";
ColorEvent = ConsoleColor.Green;
break;
case LogEvent.Warning:
Event = "WARNING";
ColorEvent = ConsoleColor.Yellow;
break;
case LogEvent.Error:
Event = "ERROR";
ColorEvent = ConsoleColor.Red;
break;
}
if (ShowConsole)
{
Console.ForegroundColor = ColorEvent;
Console.WriteLine(" [{0}] => {1}", DateTime.Now.ToString("HH:mm:ss"), Message);
Console.ResetColor();
}
if (WritelogFile)
{
if (!Directory.Exists(LogPath))
Directory.CreateDirectory(LogPath);
File.AppendAllText(LogPath + @"\" + LogSession + ".log", string.Format("[{0}] => {1}: {2}\n", DateTime.Now.ToString("HH:mm:ss"), Event, Message));
}
}
}
}
NO CONSOLE APP (ONLY LOG)
using System;
using System.IO;
namespace YOURNAMESPACEHERE
{
enum LogEvent
{
Info = 0,
Success = 1,
Warning = 2,
Error = 3
}
internal static class Log
{
private static readonly string LogSession = DateTime.Now.ToLocalTime().ToString("ddMMyyyy_HHmmss");
private static readonly string LogPath = AppDomain.CurrentDomain.BaseDirectory + "logs";
internal static void Write(LogEvent Level, string Message)
{
string Event = string.Empty;
switch (Level)
{
case LogEvent.Info:
Event = "INFO";
break;
case LogEvent.Success:
Event = "SUCCESS";
break;
case LogEvent.Warning:
Event = "WARNING";
break;
case LogEvent.Error:
Event = "ERROR";
break;
}
if (!Directory.Exists(LogPath))
Directory.CreateDirectory(LogPath);
File.AppendAllText(LogPath + @"\" + LogSession + ".log", string.Format("[{0}] => {1}: {2}\n", DateTime.Now.ToString("HH:mm:ss"), Event, Message));
}
}
Usage:
CONSOLE APP
Log.Write(LogEvent.Info, "Test message"); // It will print an info in your console, also will save a copy of this print in a .log file.
Log.Write(LogEvent.Warning, "Test message", false); // It will save the print as warning only in your .log file.
Log.Write(LogEvent.Error, "Test message", true, false); // It will print an error only in your console.
NO CONSOLE APP (ONLY LOG)
Log.Write(LogEvent.Info, "Test message"); // It will print an info in your .log file.
You can also take a look at the built-in .NET tracing facilities too. There's a set of trace listeners that allow you to output to a log file, but you can configure it to log into the Event viewer, or to a database (or all of them simultaneously).
http://www.codeguru.com/csharp/.net/net_debugging/tracing/article.php/c5919/NET-Tracing-Tutorial.htm
I'm using thread safe static class. Main idea is to queue the message on list and then save to log file each period of time, or each counter limit.
Important: You should force save file ( DirectLog.SaveToFile(); ) when you exit the program. (in case that there are still some items on the list)
The use is very simple: DirectLog.Log("MyLogMessage", 5);
This is my code:
using System;
using System.IO;
using System.Collections.Generic;
namespace Mendi
{
/// <summary>
/// class used for logging misc information to log file
/// written by Mendi Barel
/// </summary>
static class DirectLog
{
readonly static int SAVE_PERIOD = 10 * 1000;// period=10 seconds
readonly static int SAVE_COUNTER = 1000;// save after 1000 messages
readonly static int MIN_IMPORTANCE = 0;// log only messages with importance value >=MIN_IMPORTANCE
readonly static string DIR_LOG_FILES = @"z:\MyFolder\";
static string _filename = DIR_LOG_FILES + @"Log." + DateTime.Now.ToString("yyMMdd.HHmm") + @".txt";
readonly static List<string> _list_log = new List<string>();
readonly static object _locker = new object();
static int _counter = 0;
static DateTime _last_save = DateTime.Now;
public static void NewFile()
{//new file is created because filename changed
SaveToFile();
lock (_locker)
{
_filename = DIR_LOG_FILES + @"Log." + DateTime.Now.ToString("yyMMdd.HHmm") + @".txt";
_counter = 0;
}
}
public static void Log(string LogMessage, int Importance)
{
if (Importance < MIN_IMPORTANCE) return;
lock (_locker)
{
_list_log.Add(String.Format("{0:HH:mm:ss.ffff},{1},{2}", DateTime.Now, LogMessage, Importance));
_counter++;
}
TimeSpan timeDiff = DateTime.Now - _last_save;
if (_counter > SAVE_COUNTER || timeDiff.TotalMilliseconds > SAVE_PERIOD)
SaveToFile();
}
public static void SaveToFile()
{
lock (_locker)
if (_list_log.Count == 0)
{
_last_save = _last_save = DateTime.Now;
return;
}
lock (_locker)
{
using (StreamWriter logfile = File.AppendText(_filename))
{
foreach (string s in _list_log) logfile.WriteLine(s);
logfile.Flush();
logfile.Close();
}
_list_log.Clear();
_counter = 0;
_last_save = DateTime.Now;
}
}
public static void ReadLog(string logfile)
{
using (StreamReader r = File.OpenText(logfile))
{
string line;
while ((line = r.ReadLine()) != null)
{
Console.WriteLine(line);
}
r.Close();
}
}
}
}
add this config file
*************************************************************************************
<!--Configuration for file appender-->
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
<log4net>
<appender name="FileAppender" type="log4net.Appender.FileAppender">
<file value="logfile.txt" />
<appendToFile value="true" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%d [%t] %-5p [%logger] - %m%n" />
</layout>
</appender>
<root>
<level value="DEBUG" />
<appender-ref ref="FileAppender" />
</root>
</log4net>
</configuration>
*************************************************************************************
<!--Configuration for console appender-->
<configuration>
<configSections>
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,
log4net" />
</configSections>
<log4net>
<appender name="ConsoleAppender" type="log4net.Appender.ConsoleAppender" >
<layout type="log4net.Layout.PatternLayout">
<param name="ConversionPattern" value="%d [%t] %-5p [%logger] - %m%n" />
</layout>
</appender>
<root>
<level value="ALL" />
<appender-ref ref="ConsoleAppender" />
</root>
</log4net>
</configuration>
I would recommend log4net.
You would need multiple log files. So multiple file appenders. Plus you can create the file appenders dynamically.
Sample Code:
using log4net;
using log4net.Appender;
using log4net.Layout;
using log4net.Repository.Hierarchy;
// Set the level for a named logger
public static void SetLevel(string loggerName, string levelName)
{
ILog log = LogManager.GetLogger(loggerName);
Logger l = (Logger)log.Logger;
l.Level = l.Hierarchy.LevelMap[levelName];
}
// Add an appender to a logger
public static void AddAppender(string loggerName, IAppender appender)
{
ILog log = LogManager.GetLogger(loggerName);
Logger l = (Logger)log.Logger;
l.AddAppender(appender);
}
// Create a new file appender
public static IAppender CreateFileAppender(string name, string fileName)
{
FileAppender appender = new
FileAppender();
appender.Name = name;
appender.File = fileName;
appender.AppendToFile = true;
PatternLayout layout = new PatternLayout();
layout.ConversionPattern = "%d [%t] %-5p %c [%x] - %m%n";
layout.ActivateOptions();
appender.Layout = layout;
appender.ActivateOptions();
return appender;
}
// In order to set the level for a logger and add an appender reference you
// can then use the following calls:
SetLevel("Log4net.MainForm", "ALL");
AddAppender("Log4net.MainForm", CreateFileAppender("appenderName", "fileName.log"));
// repeat as desired
Sources/Good links:
Log4Net: Programmatically specify multiple loggers (with multiple file appenders)
Adding appenders programmatically
How to configure log4net programmatically from scratch (no config)
Plus the log4net also allows to write into event log as well. Everything is configuration based, and the configuration can be loaded dynamically from xml at runtime as well.
Edit 2:
One way to switch log files on the fly: Log4Net configuration file supports environment variables:
Environment.SetEnvironmentVariable("log4netFileName", "MyApp.log");
and in the log4net config:
<param name="File" value="${log4netFileName}".log/>
Use the Nlog http://nlog-project.org/. It is free and allows to write to file, database, event log and other 20+ targets. The other logging framework is log4net - http://logging.apache.org/log4net/ (ported from java Log4j project). Its also free.
Best practices are to use common logging - http://commons.apache.org/logging/ So you can later change NLog or log4net to other logging framework.
You can use http://logging.apache.org/ library and use a database appender to collect all your log info together.
We did a lot of research into logging, and decided that NLog was the best one to use.
Also see log4net vs. Nlog and http://www.dotnetlogging.com/comparison/
You could use the Apache log4net library:
using System;
using log4net;
using log4net.Config;
public class MyApp
{
// Define a static logger variable so that it references the
// Logger instance named "MyApp".
private static readonly ILog log = LogManager.GetLogger(typeof(MyApp));
static void Main(string[] args)
{
XmlConfigurator.Configure(new System.IO.FileInfo(@"..\..\resources\log4net.config"));
log.Info("Entering application.");
Console.WriteLine("starting.........");
log.Info("Entering application.");
log.Error("Exiting application.");
Console.WriteLine("starting.........");
}
}
Source: Stackoverflow.com