Finding the O/S process that is running your Oracle process    Sept 6th 2008

For many reasons, you may want to know the Operating System Process ID that is responsible for running your Oracle process.  Sometimes it might be needed to use O/S command to kill the process.

The following command will just do that

 SQL> select p.spid,s.username usrname
     from v$process p, v$session s
     where p.addr=s.paddr
     and s.username=user;