title: Using logback, but somehow log4j getting initialized
body: <p>Our console application is using logback for logging.
  There's a logback.xml file in the classpath.</p>
  
  <p>Logging works as expected (via logback) on most platforms (Linux, Windows, jdk7 or jdk8).</p>
  
  <p>However, on Macs using jdk 6, when running the app we sometimes see:</p>
  
  <pre><code>log4j:WARN No appenders could be found for logger (our.class.Here).
  log4j:WARN Please initialize the log4j system properly.
  </code></pre>
  
  <p>It seems for some reason log4j is chosen for logging instead of logback.
  In our.class.Here we log through slf4j:</p>
  
  <pre><code>private static final org.slf4j.Logger LOG = org.slf4j.LoggerFactory.getLogger(our.class.Here.class);
  </code></pre>
  
  <p>This is the complete classpath:</p>
  
  <pre><code>/path/etc/logback.xml:/path/lib/pdfbox-1.8.4.jar:/path/lib/fontbox-1.8.4.jar:/path/lib/jempbox-1.8.4.jar:/path/lib/jcl-over-slf4j-1.7.7.jar:/path/lib/bcprov-jdk15-1.45.jar:/path/lib/bcmail-jdk15-1.45.jar:/path/lib/xmlgraphics-commons-1.5.jar:/path/lib/icepdf-core-5.0.4.jar:/path/lib/jai-codec-1.1.3.jar:/path/lib/jai-core-1.1.3.jar:/path/lib/jewelcli-0.6.jar:/path/lib/commons-lang3-3.1.jar:/path/lib/commons-io-2.2.jar:/path/lib/logback-classic-1.1.0.jar:/path/lib/logback-core-1.1.0.jar:/path/lib/itext-2.1.7.jar:/path/lib/hibernate-validator-4.2.0.Final.jar:/path/lib/slf4j-api-1.7.5.jar
  </code></pre>
  
  <p>How could we troubleshoot further to understand why log4j instead of logback is chosen for logging?</p>
  
  <p>Thanks for your suggestions.</p>