Command Sample

create or replace directory DPUMP_DIR as '/oracle/dump';
select directory_path from dba_directories where upper(directory_name) = 'DPUMP_DIR';
grant all on directory DPUMP_DIR to user;
expdp user/userpass@ORCL directory=DPUMP_DIR dumpfile=DATA_PUMP.dmp logfile=DATA_PUMP.log
impdp user/userpass@ORCL directory=DPUMP_DIR dumpfile=DATA_PUMP.dmp logfile=DATA_PUMP.log

Trouble Shooting
1.impdp error:ORA-06512: at “SYS.UTL_FILE”

sh>impdp ccas/password directory=dump_dir dumpfile=ccasdb%u.dmp parallel=5
ORA-39002: invalid operation
ORA-39070: Unable to open the log file.
ORA-29283: invalid file operation
ORA-06512: at "SYS.UTL_FILE", line 488
ORA-29283: invalid file operation
因/ccas/dmp目录的权限为drwxr-xr-x,其它用户没有写权限,而impdp运行时的权限是oracle用户的权限,
而不是当前登录用户的权限,impdp不能写dmp目录,所以需将dmp目录加上o+w权限。
sh>chmod 777 /ccas/dmp
sh>ls –l /ccas
drwxrwxrwx   2 ccas       ccas          1024 6月 4日 09:40 dmp
重新运行impdp后成功

Reference:
1.impdp(Data Pump Import),http://docs.oracle.com/cd/B19306_01/server.102/b14215/dp_import.htm
2.expdp(Data Pump Export),http://docs.oracle.com/cd/E11882_01/server.112/e22490/dp_export.htm