how to check blockers in oracle 10g, 11g

set echo off

column blocker format a11;

column blockee format a10;

column sid format 99999;

select

           (select username from v$session where sid=a.sid) blocker,

         a.sid,

       ' is blocking ' "IS BLOCKING",

         (select username from v$session where sid=b.sid) blockee,

             b.sid

    from v$lock a, v$lock b

   where a.block = 1

     and b.request > 0

     and a.id1 = b.id1

     and a.id2 = b.id2

/

select ctime/60,sid from v$lock where block>0;  

select program,ACTION,STATUS,serial# from v$session where sid='&sid';

SELECT substr(DECODE(request,0,'Holder: ','Waiter: ')||sid,1,12) sess, id1, id2, lmode, request, type FROM GV$LOCK WHERE (id1, id2, type) IN (SELECT id1,id2,type FROM GV$LOCK WHERE request>0) order by id1;

select sid, serial#, action, module, program, status, last_Call_ET/60 as LCET_min from gv$session where sid in

(select session_id from dba_locks where blocking_others='Blocking')

select sid, b.serial#, osuser, b.username, status, process, paddr, spid

from v$process a,v$session b

where sid = '&sid'

and a.addr = b.paddr

and b.username != ' '

order by 1

select sql_text

  from   v$session, v$sqltext

  where v$session.sql_address = v$sqltext.address

  and   V$session.sql_hash_value = v$sqltext.hash_value

  and  sid = &sid

order by piece