在之前的文章中有三篇提到了Oracle的监听，如下：
Oracle Listener 动态注册 与 静态注册
Oracle 监听(Listener) 中 services 说明
Oracle 数据库监听配置
Oracle的监听(Listener)在缺省情况下，会在文件中记录日志，记录数据库实例注册操作、客户端的连接等。
Oracle 11g中的信息如下：
[oracle@dave ~]$ lsnrctl status
LSNRCTL for Linux: Version 11.2.0.3.0 - Productionon 22-DEC-2012 21:36:43
Copyright (c) 1991, 2011, Oracle. All rights reserved.
Connecting to(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.1.4)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version11.2.0.3.0 - Production
Start Date 22-DEC-2012 21:31:53
Uptime 0 days 0 hr. 4 min. 50 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
Listener Log File /u01/app/oracle/diag/tnslsnr/dave/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.1.4)(PORT=1521)))
Services Summary...
Service "dave" has 2 instance(s).
Instance "dave", status UNKNOWN, has 1 handler(s) for thisservice...
Instance "dave", status READY, has 1 handler(s) for thisservice...
Service "daveXDB" has 1instance(s).
Instance "dave", status READY, has 1 handler(s) for thisservice...
The command completed successfully