https://www.cnblogs.com/kerrycode/p/3591390.html --参考
今天在启动oracle 11g R2数据库的监听程序lsnrctl 的时候，出现错误提示，不能正常启动，错误提示如下：

[oracle@rhel5 ~]$ lsnrctl start
LSNRCTL for Linux: Version 11.2.0.5.0 - Production on 06-SEP-2013 05:31:02
Copyright © 1991, 2011, Oracle. All rights reserved.
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=rhel5)(PORT=1521))
TNS-12541: TNS:no listener
TNS-12560: TNS:protocol adapter error
TNS-00511: No listener
Linux Error: 111: Connection refused

[oracle@getlnx01 admin]$ lsnrctl status

LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 09-MAR-2015 09:13:29

Copyright © 1991, 2007, Oracle. All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1)))

TNS-12541: TNS:no listener

TNS-12560: TNS:protocol adapter error

TNS-00511: No listener

Linux Error: 111: Connection refused

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=getlnx01.esqule.com)(PORT=1521)))

TNS-12541: TNS:no listener

TNS-12560: TNS:protocol adapter error

TNS-00511: No listener

Linux Error: 111: Connection refused

[oracle@getlnx01 dbs]$ lsnrctl start

LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 09-MAR-2015 09:20:46

Copyright © 1991, 2007, Oracle. All rights reserved.

Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait…

TNSLSNR for Linux: Version 10.2.0.4.0 - Production

System parameter file is /u01/app/oracle/product/10.2.0/db_1/network/admin/listener.ora

Log messages written to /u01/app/oracle/product/10.2.0/db_1/network/log/listener.log

Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1)))

Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=getlnx01.esqule.com)(PORT=1521)))

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1)))

TNS-12547: TNS:lost contact

TNS-12560: TNS:protocol adapter error

TNS-00517: Lost contact

Linux Error: 104: Connection reset by peer

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=getlnx01.esqule.com)(PORT=1521)))

TNS-12541: TNS:no listener

TNS-12560: TNS:protocol adapter error

TNS-00511: No listener

Linux Error: 111: Connection refused

检查了监听配置文件listener.ora, 发现没有问题.Google搜索了一下: 这个错误跟Linux的主机名和IP配置有关系，于是赶紧检查：

[oracle@EGMLNX02 admin]$ hostname
EGMLNX02.egm1.esquel.com
[oracle@EGMLNX02 admin]$ more /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=EGMLNX02.egm1.esquel.com

结果发现主机名和IP配置文件 hosts里面，不知道是系统管理员手误还是其它原因，在hosts文件，127.0.0.1配置里面多了一项EGMLNX02(应该为三项),结果导致ORACLE数据库监听服务器启动报错

关于主机名和IP配置文件,一般情况下hosts文件的每行为一个主机，每行由三部份组成，每个部份由空格隔开。其中#号开头的行做说明，不被系统解释。
第一部份：网络IP地址；
第二部份：主机名或域名；
第三部份：主机名别名；

于是修改hosts文件，然后重新启动监听，OK，文件解决了。