Change name of logfile a few times during runtime

Question

Is it possible to change the name of a logfile for a fileappender while the application is running? It will be done a few times / day.

I'll try to elaborate myself a bit more: my app writes firmware on a device. All the devices the user already worked on, are in a grid. The user can start a new writing-wizard or can resume or restart the action on an already started device. What I would like to do is keep a log of all the steps performed by the user for a certain device.

For example: when the user works on device AB0124, I want to write to a logfile called AB0124.log. When he ends working on that device and starts on device XY5618 I want to log those actions in XY5618.log

I've read that it's possible to use a context-property (here and here and a lot of other posts), but you have to set the property before creating the logger. So, instead of creating a logger in the class, I create one in my method after setting the property. But so far, nothing gets logged.

When I set the filename hardcoded in the config, it's working. Am I missing somehting here?

Log4Net.config:

<appender name="StepsLogAppender" type="log4net.Appender.FileAppender">
  <filter  type="log4net.Filter.LevelMatchFilter">
    <levelToMatch value="INFO"/>
  </filter>
  <filter type="log4net.Filter.DenyAllFilter" />
  <file type="log4net.Util.PatternString" value="%property{LogPathModifier}" />
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date{dd/MM/yyyy  -  HH:mm:ss} - %message%newline" />
  </layout>
</appender>

<root>
  <level value="ALL" />
  <appender-ref ref="StepsLogAppender" />
</root>

C#:

public void WriteStepInfo(string device, int step)
{
    log4net.ThreadContext.Properties["LogPathModifier"] = string.Format("D:\\StepsDevice_{0}.txt", device);
    var log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
    log.Info(string.Format("Device {0} - step {1}.", device, step));
}

And in the AssemblyInfo.cs:

[assembly: log4net.Config.XmlConfigurator(ConfigFile = "Log4Net.config", Watch = true)]

Answer 1

The answer of Peter brought me in the right direction, but I ended up doing it in code instead of editing and saving the config-file.

public void WriteStepInfo(string device, int step)
{
    var h = (log4net.Repository.Hierarchy.Hierarchy)LogManager.GetRepository();
    foreach (IAppender a in h.Root.Appenders)
    {
        if (a.Name == "StepsLogAppender")
        {
            FileAppender fa = (FileAppender)a;
            var logFileLocation = string.Format(".\\Logs\\Device_{0}.log", device);

            fa.File = logFileLocation;
            fa.ActivateOptions();
            break;
        }
    }

    Log.Info(string.Format("Device {0} - step {1}. Different file for each device", device, step));
}