FIND ORACLE SID FROM OS PID

select spid, s.sid, p.serial#, s.terminal, pid, machine, s.program, osuser,
p.program
from v$session s, v$process p
where addr = paddr and (spid like
'%&&OSID%' or process like '%&OSID%');

or

select * from v$session where paddr in (select addr from v$process where spid =&OS_PID);
or

select p.spid,s.action,s.sid,s.

serial#,s.username,s.status, s.sql_hash_value,s.last_call_et,p.program,p.terminal,logon_time,module,s.osuser
from V$process p,V$session s
where s.paddr = p.addr and s.status = 'ACTIVE' and s.username not like '%SYS%'
AND SPID=&OS_PID;

or

-- show PROCESS id for all the active sessions
select p.spid,s.action,s.sid,s.serial#,s.username,s.status, s.sql_hash_value,s.last_call_et,p.program,p.terminal,logon_time,module,s.osuser
from V$process p,V$session s
where s.paddr = p.addr and s.status = 'ACTIVE' and s.username not like '%SYS%'
--AND SPID=&OS_PID;