Learning Datapump:
SQL> create directory export as '/u01/work/export';
SQL> grant read,write on directory export to system;
expdp userid=system/manager dumpfile=expdp.dmp logfile=expdp.log full=y directory=exportparallel=4
if using "exp" watch out if some columns with property 1073741824 (see the column value PROPERTY in COL$ for column COL001) are columns with defaults that are not saved in the column. If so the imp tool is going to fail ORA-1400 During Import of Export Dump Written in Direct Path Mode. So the work around is using expdp or not using Direct Path mode during the export.
select col#, name, property
from col$
where obj# in (select object_id
from dba_objects
where owner = 'TEST' and
object_name = 'A_TAB');
Another trick to extract an schema (indexes in this case) or part of a schema using imp tool:
imp system/manager parfile=indexes.par
[oracle@rac1 indexes]$ more indexes.par
FILE=../dat1.dmp
FEEDBACK=100000
BUFFER=100000000
LOG=indexes.log
INDEXFILE=indexes.sql
FROMUSER=DRAW_SUM_TEST,REPORTING,ADMIN,GGE,LOTTERY,GENDBA
TOUSER=DRAW_SUM_TEST,REPORTING,ADMIN,GGE,LOTTERY,GENDBA
IGNORE=Y