错误具体描述：

ERROR:

ORA-01034: ORACLE not available

ORA-27101: shared memory realm does not exist

进程 ID: 0

会话 ID: 0 序列号: 0

解决方式：

1.执行

[oracle@AY140316135826Z admin]$ sqlplus 'sys/Hello54987663@localhost:1521/orcl as sysdba'

2.执行：

SQL>startup

3.测试一下：

SQL>select * from user_tables;

ok显示除了很多结果！

此时tnsnames.ora内容：

# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.

orcl =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SID = orcl)
    )
  )
listener.ora内容：

# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
# Generated by Oracle configuration tools.

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
  )

SID_LIST_LISTENER=
  (SID_LIST=
	(SID_DESC=
         (GLOBAL_DBNAME=orcl)
         (SID_NAME=orcl)			
         (ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1/)
       )
      )

附录：

oracle监听启动执行：

lsnrctl start