How do I find what Java version Tomcat6 is using?

/usr/local/tomcat6/bin/catalina.sh version

At first you need to understand first, that Tomcat is a Java application. So, to see which java version Tomcat is using, you can just simply find the script file from which Tomcat is started, usually catalina.sh.

Inside this file, you will get something like below:

catalina.sh:#   JAVA_HOME       Must point at your Java Development Kit installation.
catalina.sh:#                   Defaults to JAVA_HOME if empty.
catalina.sh:  [ -n "$JAVA_HOME" ] && JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
catalina.sh:  JAVA_HOME=`cygpath --absolute --windows "$JAVA_HOME"`
catalina.sh:    echo "Using JAVA_HOME:       $JAVA_HOME"

By default, JAVA_HOME should be empty, which mean it will use the default version of java, or you can test with: echo $JAVA_HOME

And then use "java -version" to see which version you default java is.

And vice versa by setting this property: JAVA_HOME, you can configure which Java version to use when starting Tomcat.

Once you have started tomcat simply run the following command at a terminal prompt:

ps -ef | grep tomcat

This will show the process details and indicate which JVM (by folder location) is running tomcat.