如连接果在以rman数据库如果指定@db_name时，如果报如下错误

[oracle@localhost Desktop]$ rman target sys/jume123456@test

Recovery Manager: Release 11.2.0.1.0 - Production on Sat Aug 31 08:53:12 2013

Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-00554: initialization of internal recovery manager package failed
RMAN-04005: error from target database:
ORA-12154: TNS:could not resolve the connect identifier specified
则是由于没有配置正确tnsnames.ora，正确配置如下：

TEST =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = test)
    )
  )