Hello, How can i set the log filename set during the init() of my StartupServlet. I tried using MDC but it's not working for me. What happens is the file is not created. Instead a file with name "%exp{logFileName}" is created on my web server's bin directory. In my StartupServlet, I have this init method that calls MDC.put(). public void init() throws ServletException { MDC.put("logFileName", "c:\\testlogs\\test.log"); Logger log = LoggerFactory.getLogger(StartupServlet.class); log.info("This should be logged"); } In my logback.xml, I have a MDC.get(). <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender"> <append>true</append> <expression name="logFileName">MDC.get("logFileName")</expression> <file>%exp{logFileName}</file> ... I'm new with logback, thanks in advance for your help! I'm trying to follow Ceki's example in his blog http://ceki.blogspot.com/2006/10/repated-configuration-with-joran.html thanks, jenny