How Java Reads OS Env Variables ?

I am using JDK 1.3 right now. Before that I used to use System.getenv to retrieve OS env var. But getenv in 1.3 is deprecated. Is there other way to read env var ? I understand that properties file or even LDAP is the latest preferred way. But my system need to share the same env var with other concurrent systems, e.g. ApplEnv=uat …etc.

Thanks.
Jim