Get log4net log file in C#

Question

This is my configuration for log4net:

<log4net>
    <appender name="MyLogger" type="log4net.Appender.RollingFileAppender">
        <file value="MyLog.log" />
        <appendToFile value="true" /> 
        <rollingStyle value="Size"/>
        <maxSizeRollBackups value="20"/>
        <maximumFileSize value="1000KB"/>
        <layout type="log4net.Layout.PatternLayout">
            <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss},%p,%m%n" />
        </layout>
    </appender>
    <root>
        <level value="DEBUG" />
        <appender-ref ref="MyLogger" />
    </root>
</log4net>

In C# I'm trying to get the name of the log file (which is MyLog.log). I googled and tried many things but failed to do so. Any help?

Thanks!

Answer 1

Solution is quite easy in your situation; just use this code:

var rootAppender = ((Hierarchy)LogManager.GetRepository())
                                         .Root.Appenders.OfType<FileAppender>()
                                         .FirstOrDefault();

string filename = rootAppender != null ? rootAppender.File : string.Empty;

Answer 2

When having multiple file appenders, you might want to get them by name. Also to make sure to get the appender even if it is not referenced by the root node, the following code helps:

public static string GetLogFileName(string name)
{
     var rootAppender = LogManager.GetRepository()
                                  .GetAppenders()
                                  .OfType<FileAppender>()
                                  .FirstOrDefault(fa => fa.Name == name);

     return rootAppender != null ? rootAppender.File : string.Empty;
}

Answer 3

Since I already had a logger defined in the class I just used it. One thing to be aware of is that there may be more than one appender and often the first one is the console (which doesn't have a file). Here is my solution for what its worth.

using log4net;
using log4net.Appender;
using log4net.Repository;

namespace MyNameSpace {
public class MyClass {

    private static readonly ILog logger = LogManager.GetLogger(typeof(MyClass));

    public String GetLogFileName() {

        String filename = null;

        IAppender[] appenders = logger.Logger.Repository.GetAppenders();
        // Check each appender this logger has
        foreach (IAppender appender in appenders) {
            Type t = appender.GetType();
            // Get the file name from the first FileAppender found and return
            if (t.Equals(typeof(FileAppender)) || t.Equals(typeof(RollingFileAppender))) {
                filename = ((FileAppender)appender).File;
                break;
            }
        }
        return filename;
    }
}

}

Answer 4

        String filename = null;

        Hierarchy hierarchy = LogManager.GetRepository() as Hierarchy;
        Logger logger = hierarchy.Root;

        IAppender[] appenders = logger.Repository.GetAppenders();

        // Check each appender this logger has
        foreach (IAppender appender in appenders)
        {
            Type t = appender.GetType();
            // Get the file name from the first FileAppender found and return
            if (t.Equals(typeof(FileAppender)) || t.Equals(typeof(RollingFileAppender)))
            {
                filename = ((FileAppender)appender).File;
                break;
            }
        }

        System.Diagnostics.Process.Start(filename); //for example, open file in notepad

Answer 5

If your config does not have a <root> node then the above solution will not work for you. Read on.

<log4net>
  <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
    <file value="${LOCALAPPDATA}\Anonymous.log" />
    <appendToFile value="true" />
    <rollingStyle value="Size" />
    <maxSizeRollBackups value="10" />
    <maximumFileSize value="2000KB" />
    <staticLogFileName value="true" />
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />
    </layout>
  </appender>
  <logger name="AnonymousLog">
    <level value="All" />
    <appender-ref ref="RollingFileAppender" />
  </logger>
</log4net>

This retrieves the log file:

string path = (LogManager.GetCurrentLoggers()[0].Logger.Repository.GetAppenders()[0] as FileAppender).File;

The (hopefully) crash-proof version:

string path = null;
if (LogManager.GetCurrentLoggers().Length > 0 && LogManager.GetCurrentLoggers()[0].Logger.Repository.GetAppenders().Length > 0)
{
    path = (LogManager.GetCurrentLoggers()[0].Logger.Repository.GetAppenders()[0] as FileAppender).File;
}

Finally, if you get stuck with log4net add this to your <appSettings> section:

<add key="log4net.Internal.Debug" value="true"/>

Answer 6

((log4net.Appender.FileAppender)(_log.Logger.Repository.GetAppenders())[0]).File

Answer 7

I didn't find the above code working. This worked for me

var filename= ((log4net.Appender.FileAppender)(((log4net.Appender.IAppender[])((((((log4net.Repository.Hierarchy.Hierarchy)((((log4net.Core.LoggerWrapperImpl)(log)).Logger).Repository)).Root).Hierarchy.Root).Appenders).SyncRoot))[0])).File