Question

I have here this log4net config:

  <log4net>
    <root>
      <level value="DEBUG" />
      <appender-ref ref="LogFileAppender" />
    </root>
    <appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender">
      <param name="File" value="D:\logfolder\logfile.txt" />
      <param name="AppendToFile" value="true" />
      <rollingStyle value="Size" />
      <maxSizeRollBackups value="10" />
      <maximumFileSize value="20MB" />
      <staticLogFileName value="true" />
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" value="%-5p%d{yyyy-MM-dd hh:mm:ss} – %m%n" />
      </layout>
    </appender>
  </log4net>

This is working well, but I would like to create another logfile with only “INFO” input. Is it possible to log in two different files, without changing anything in my C# code, just changing the config file?
Or lets just make the question simple: What do I have to add exactly to my config file?

And also, I have another issue: if I choose “INFO” instead of “DEBUG”, I get INFO + ERROR logs. can I change this somehow, not to get ERROR logs, just INFO? Thank you.

Answer 1

You can configure second appender with filter specified, and add it to your root logger.

<log4net>
    <root>
      <level value="DEBUG" />
      <appender-ref ref="LogFileAppender" />
      <appender-ref ref="AnotherLogFileAppender" />
    </root>
    <appender name="LogFileAppender" 
              type="log4net.Appender.RollingFileAppender">
      ...
    </appender>
    <appender name="AnotherLogFileAppender" 
              type="log4net.Appender.RollingFileAppender">
      <param name="File" value="D:\logfolder\anotherlogfile.txt" />
      <param name="AppendToFile" value="true" />
      <rollingStyle value="Size" />
      <maxSizeRollBackups value="10" />
      <maximumFileSize value="20MB" />
      <staticLogFileName value="true" />
      <layout type="log4net.Layout.PatternLayout">
        <param name="ConversionPattern" 
               value="%-5p%d{yyyy-MM-dd hh:mm:ss} – %m%n" />
      </layout>
      <filter type="log4net.Filter.LevelRangeFilter">
                <param name="LevelMin" value="INFO"/>
                <param name="LevelMax" value="INFO"/>
      </filter>
    </appender>
  </log4net>

Also consider to use new style of log4net configuration, rather than old one with param tags:

<log4net>
    <root>
      <level value="DEBUG" />      
      <appender-ref ref="LogFileAppender" />
      <appender-ref ref="AnotherLogFileAppender" />
    </root>
    <appender name="LogFileAppender"
          type="log4net.Appender.RollingFileAppender">
      <file value="D:\logfolder\logfile.txt"/>
      <appendToFile value="true"/>
      <rollingStyle value="Size"/>
      <maxSizeRollBackups value="10"/>
      <maximumFileSize value="20MB"/>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%-5p%d{yyyy-MM-dd hh:mm:ss} – %m%n"/>
      </layout>
    </appender>
    <appender name="AnotherLogFileAppender" 
              type="log4net.Appender.RollingFileAppender">
      <file value="D:\logfolder\anotherlogfile.txt"/>
      <appendToFile value="true"/>
      <rollingStyle value="Size"/>
      <maxSizeRollBackups value="10"/>
      <maximumFileSize value="20MB"/>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%-5p%d{yyyy-MM-dd hh:mm:ss} – %m%n"/>
      </layout>               
      <filter type="log4net.Filter.LevelMatchFilter">
        <levelToMatch value="INFO"/>
      </filter>
    </appender>
  </log4net>