title: How do I configure starting jdk for hudson(now jenkins)?
body: <p>I googled a lot and read through the wiki, just could not find out where setting starting jdk can be done. It needs jdk 1.5 or later. The os is centOS and I set the JAVA_HOME environment variable to a 1.6 version and add jdk bin directory into PATH environment variable, when I run the command '/etc/init.d/jenkins start' , I received below error:</p>
  
  <pre><code>Jenkins requires Java5 or later, but you are running 1.4.2 from /usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre
  java.lang.UnsupportedClassVersionError: 48.0
     at Main.main(Main.java:90)
  </code></pre>
  
  <p>Don't know why jenkins look for jdk from path above, I don't see any environment variable containing /usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre. 
    Any ideas?</p>
  
  <p>========update<br>
  to firelore:</p>
  
  <p>I tried to run command 'update-alternatives --install java java  /home/irteam/app/jdk1.6.0_07 ',it doesn't work,prompting command parameters, like :</p>
  
  <pre><code>alternatives version 1.3.30.1 - Copyright (C) 2001 Red Hat, Inc.
  This may be freely redistributed under the terms of the GNU Public License.
  
  usage: alternatives --install &lt;link&gt; &lt;name&gt; &lt;path&gt; &lt;priority&gt;
                      [--initscript &lt;service&gt;]
                      [--slave &lt;link&gt; &lt;name&gt; &lt;path&gt;]*
         alternatives --remove &lt;name&gt; &lt;path&gt;
         alternatives --auto &lt;name&gt;
         alternatives --config &lt;name&gt;
         alternatives --display &lt;name&gt;
         alternatives --set &lt;name&gt; &lt;path&gt;
  
  common options: --verbose --test --help --usage --version
                  --altdir &lt;directory&gt; --admindir &lt;directory&gt;
  </code></pre>