Which sessions are using temporary tablespace, how much space is being used?

/*
The query below will display which sessions are using TEMP tablespace and how much space is
being used by each session:
*/

SELECT   b.TABLESPACE
       , b.segfile#
       , b.segblk#
       , ROUND (  (  ( b.blocks * p.VALUE ) / 1024 / 1024 ), 2 ) size_mb
       , a.SID
       , a.serial#
       , a.username
       , a.osuser
       , a.program
       , a.status
    FROM v$session a
       , v$sort_usage b
       , v$process c
       , v$parameter p
   WHERE p.NAME = 'db_block_size'
     AND a.saddr = b.session_addr
     AND a.paddr = c.addr
ORDER BY b.TABLESPACE, b.segfile#, b.segblk#, b.blocks;


/*
To see how much space is being used and free in TEMP tablespace run the following sql:
*/

SELECT tablespace_name, SUM(bytes_used), SUM(bytes_free)
FROM   v$temp_space_header
GROUP  BY tablespace_name;


/*
Run the following statement to check the free space within the used portion of TEMPFILE (if
you are running older version of Oracle and don't have tempfile you can replace v$tempfile
with v$datafile):
*/

SELECT   A.tablespace_name tablespace, D.mb_total,
         SUM (A.used_blocks * D.block_size) / 1024 / 1024 mb_used,
         D.mb_total - SUM (A.used_blocks * D.block_size) / 1024 / 1024 mb_free
FROM     v$sort_segment A,
         (
         SELECT   B.name, C.block_size, SUM (C.bytes) / 1024 / 1024 mb_total
         FROM     v$tablespace B, v$tempfile C
         WHERE    B.ts#= C.ts#
         GROUP BY B.name, C.block_size
         ) D
WHERE    A.tablespace_name = D.name
GROUP by A.tablespace_name, D.mb_total;