Best way to dynamically set an appender file path

Question

I am trying to find somebody smarter than me to validate some syntax I wrote up. The idea is to configure the filename of my RollingFileAppender to the name of the assembly

Answer 1

it worked for me with the date <file type="log4net.Util.PatternString" value="./Log/logQueueService%date{yyyy_MM_dd}.log" />

Answer 2

You are doing this the hard way! Define your log4net config as XML in your application's configuration file and use %property{} to advantage:

<appender name="YourAppender" type="log4net.Appender.RollingFileAppender">
  <file type="log4net.Util.PatternString" value="~/App_Data/%property{LogName}" />
  ....
</appender>

This is dynamic -- you just have to set the log4net property "LogName" before you initialize log4net. Thus, in your code any time before you configure log4net, set the desired value of this property:

string LogName = GetType().Assembly.GetName().Name + ".log";
log4net.GlobalContext.Properties["LogName"] = LogName;

Of course, you may use any property name. I've chosen "LogName" for a simple example, but you can have one per application if you want, as long as your code knows what the correct property name is and what the correct value should be.

Answer 3

In 2015, we do it like this:

<file type="log4net.Util.PatternString">
  <conversionPattern value="%appdomain.log" />
</file>

No other code required.

App domain is the executing assembly's file name.

Answer 4

Here is way to set or change the logfile of the first appender at runtime:

var appender = (log4net.Appender.FileAppender)LogManager.GetRepository().GetAppenders()[0];
appender.File = "C:\whatever.log";
appender.ActivateOptions();