How to derive the process ID of its own session?

Requirements:

How to derive the OS process ID of its OWN Oracle session? Assumption is that we have access to V$PROCESS.

In 10g, I solved it this way:

From userenv('PID') this get mapped to the PID field of V$PROCESS. So I just derived the OS process ID (which is in the V$PROCESS.SPID field) by searching through V$Process for the corresponding USERENV('PID'). But in 9iR2, userenv('PID') is not a valid parameter. So what is the equivalent parameter to be passed to userenv()?

Thank you very much.

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