HOW TO MATCH OS PROCESS WITH ORACLE SESSION

Check for OS PID running on the database through TOP command.

SET LONG 200000000
SET LINES 300
SET PAGES 999
COL OSUSER FOR A6
COL DBUSER FOR A6
COL SID FOR 9999
COL SERIAL# FOR 9999999
COL PID FOR A8
COL SQL_ID FOR A15
COL STATUS FOR A10
COL CONNECTED_FROM FOR A20
COL MODULE FOR A10
COL PORT FOR 9999999
COL PROGRAM FOR A20
COL ACTIVE_TIME_SEC FOR 9999999999
COL PARSING_SCHEMA_NAME FOR A20 
COL SQL_FULLTEXT FOR A60

SELECT S.OSUSER,
       S.USERNAME DBUSER,
       S.SID,
       S.SERIAL#,
       P.SPID PID,
       S.SQL_ID,
       S.STATUS,
       S.MACHINE CONNECTED_FROM,
       S.PORT,
       S.PROGRAM,
       S.LAST_CALL_ET ACTIVE_TIME_SEC,
       Q.SQL_FULLTEXT
FROM
       V$SESSION S,
       V$PROCESS P,
       V$SQL Q
WHERE
       S.PADDR=P.ADDR AND
       S.SQL_ID=Q.SQL_ID AND 
       S.SQL_CHILD_NUMBER=Q.CHILD_NUMBER AND
       P.SPID=&PID;