If you need to rebuild your temp tablespace, eg the existing one is corrupt or the wrong size, the trick is to temporarily give oracle a new one to use as its default temp tablespace while you replace the real one, then switch back.

create temporary tablespace TEMP_TMP
 tempfile '/oracle/oradata/IFSS/temp02.dbf'
 size 1G reuse
 autoextend on next 100M maxsize unlimited;
alter database default temporary tablespace TEMP_TMP;
drop tablespace TEMP;
! rm /oracle/oradata/IFSS/temp01.dbf
create temporary tablespace TEMP
 tempfile '/oracle/oradata/IFSS/temp01.dbf'
 size 1G reuse
 autoextend on next 100M maxsize unlimited;
alter database default temporary tablespace TEMP;
drop tablespace TEMP_TMP;
! rm /oracle/oradata/IFSS/temp02.dbf
select * from dba_temp_files;
select * from dba_tablespaces;

Jowan points out below that “reuse” is better omitted.