First, you will need to determine the command and/or environment settings used when starting the Java application.
If the application is started with a script, you will need to check the script: there might be lines that set JAVA_HOME and/or PATH environment variables to point to a particular version of Java.
If the Java version is not determined explicitly at the application start-up script, you will need to look at the environment of the user that normally runs the application. The login scripts for that user might include JAVA_HOME and/or PATH settings that determine which version of Java will be used by default by that user.
If there are no application-specific nor user-specific settings, then you might use "which java" to see the pathname of the default Java interpreter (if there is a default Java interpreter).
Also, "java -version" might be useful to identify the manufacturer of a particular instance of Java.
If you see a "java" process in the process listing and want to know which version of Java it uses, make note of the PID of the process, then run "ls -l /proc/<PID>/exe". That will tell you the exact pathname of the java binary it uses.
Through the proc filesystem you can also take a peek at the environment variables of any running process, with a command like "strings /proc/<PID>/environ | less".
MK
