title: How to use external log4j.properties for multiple projects?
body: <p>I have a main project, which depends on multiple projects (in eclipse).</p>
  
  <p>At the end of the project, I will generate a runnable jar and a log4j.properties. This properties file is an external file, so my client can modify it at will (email address etc).</p>
  
  <p>runnable.jar + log4j.properties.</p>
  
  <p>At the same time, those projects which the main project depends on, have their own log4j properties files.</p>
  
  <p>I want to centralize the setting in log4j.properties into one external file. How to do that?</p>