Log4j: How to configure simplest possible file logging?

Question

My story:

I want to make a thing which is as simple as a simplest possible log4j logger that logs rows to a file. I have found several examples with some functionality, but not a basic, general one that really works, and not one with an explanation how the each row work.

Question:

Could anybody provide one?

Prerequisites:

• I already know where to put the file and I have the log4j configured and working for console logging.
  
• Now I want to log to a file and also find the file from file system once the program has run.
  
• Rows needed to be added to the existing log4j.properties file are the desired output.

Answer 1

I have one generic log4j.xml file for you:

<?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd" > <log4j:configuration debug="false">      <appender name="default.console" class="org.apache.log4j.ConsoleAppender">         <param name="target" value="System.out" />         <param name="threshold" value="debug" />         <layout class="org.apache.log4j.PatternLayout">             <param name="ConversionPattern" value="%d{ISO8601} %-5p [%c{1}] - %m%n" />         </layout>     </appender>      <appender name="default.file" class="org.apache.log4j.FileAppender">         <param name="file" value="/log/mylogfile.log" />         <param name="append" value="false" />         <param name="threshold" value="debug" />         <layout class="org.apache.log4j.PatternLayout">             <param name="ConversionPattern" value="%d{ISO8601} %-5p [%c{1}] - %m%n" />         </layout>     </appender>      <appender name="another.file" class="org.apache.log4j.FileAppender">         <param name="file" value="/log/anotherlogfile.log" />         <param name="append" value="false" />         <param name="threshold" value="debug" />         <layout class="org.apache.log4j.PatternLayout">             <param name="ConversionPattern" value="%d{ISO8601} %-5p [%c{1}] - %m%n" />         </layout>     </appender>      <logger name="com.yourcompany.SomeClass" additivity="false">         <level value="debug" />         <appender-ref ref="another.file" />     </logger>      <root>         <priority value="info" />         <appender-ref ref="default.console" />         <appender-ref ref="default.file" />     </root> </log4j:configuration> 

with one console, two file appender and one logger poiting to the second file appender instead of the first.

EDIT

In one of the older projects I have found a simple log4j.properties file:

# For the general syntax of property based configuration files see # the documentation of org.apache.log4j.PropertyConfigurator.  # The root category uses two appenders: default.out and default.file. # The first one gathers all log output, the latter only starting with  # the priority INFO. # The root priority is DEBUG, so that all classes can be logged unless  # defined otherwise in more specific properties. log4j.rootLogger=DEBUG, default.out, default.file  # System.out.println appender for all classes log4j.appender.default.out=org.apache.log4j.ConsoleAppender log4j.appender.default.out.threshold=DEBUG log4j.appender.default.out.layout=org.apache.log4j.PatternLayout log4j.appender.default.out.layout.ConversionPattern=%-5p %c: %m%n  log4j.appender.default.file=org.apache.log4j.FileAppender log4j.appender.default.file.append=true log4j.appender.default.file.file=/log/mylogfile.log log4j.appender.default.file.threshold=INFO log4j.appender.default.file.layout=org.apache.log4j.PatternLayout log4j.appender.default.file.layout.ConversionPattern=%-5p %c: %m%n 

For the description of all the layout arguments look here: log4j PatternLayout arguments