You can use the -XshowSettings flag in the Hotspot JVM version 1.7 and up (not supported in 1.6):
**java -XshowSettings:properties -version**
OpenJDK has had support for this flag since late 2010.
The Oracle JVM ships with the tool jcmd which allows you to see the flags present in a running JVM. See:
For this use case, you could use:
**jcmd <pid> VM.system_properties**