I'd like to point out a factual error on this page. It says:
> In Tomcat(5.5), if no custom logger is defined (log4J) then everything is logged via Commons Logging
Commons Logging is a logging API, not a logging implementation. Log4J is a logging implementation that Commons Logging will use by preference if log4j.jar is on the classpath. Otherwise, CL will use the logging implementation in the java.util package, which presumably is creating the catalina.log file this page complains about. Blaming Commons Logging for a limitation of a particular logging implementation is like blaming the JDBC API for a badly-implemented JDBC driver.