Reading Java system properties from command line

Question

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.

Seen in http://marxsoftware.blogspot.de/2016/02/hotspot-jvm-XshowSettings.html

EDIT 14 Dec 2016

The Oracle JVM ships with the tool jcmd which allows you to see the flags present in a running JVM. See:

https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr006.html

For this use case, you could use:

jcmd <pid> VM.system_properties

But there are also many other useful commands. For example:

jcmd <pid> VM.flags
jcmd <pid> VM.command_line
jcmd <pid> GC.run