What system properties are set by OpenJDK's vm that differentiate it from Sun/Oracle's vm?

Question

Question: What system properties are set by OpenJDK's vm so that I can identify that I am running under OpenJDK and not under Sun/Oracle's vm?

As shown here: https://gist.github.com/sinewalker/3890869, the following system properties are NOT sufficient for differentiating between OpenJDK's VM and Sun/Oracle's VM:

System properties:

System.out.println(System.getProperty("java.vendor"));
System.out.println(System.getProperty("java.vendor.url"));
System.out.println(System.getProperty("java.version"));

Outputs the following using OpenJDK's vm (these are the same values you would see on Sun's VM):

Sun Microsystems Inc.
http://java.sun.com/
1.6.0_24

I was expecting the property values to reflect what is output by the java command:

$ java -version
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.4) (6b24-1.11.4-1ubuntu0.12.04.1)
OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)

Answer 1

Try using these:

System.out.println(System.getProperty("java.vm.version"));
System.out.println(System.getProperty("java.runtime.name"));
System.out.println(System.getProperty("java.vm.name"));

You might also like System#getProperties():

System.getProperties().list(System.out);

which will list all the current System properties, to System.out.