Tns-12541:tns:no Listener TNS-12560 Tns-00511:no Listener

To test the need, the system administrator helped to clone an Oracle database server to a virtual machine, I went up to delete the root, Oracle, Tomcat account crontab timed job, and then launched an Oracle database instance, delete the job under Oracle, And then start the listening times the following error:

[oracle@egmlnx02 admin]$ Lsnrctl Stop

Lsnrctl for linux:version 10.2.0.4.0-production on 10-mar-2014 09:15:44

Copyright (c) 1991, 2007, Oracle. All rights reserved.

Connecting to (description= address= (protocol=tcp) (host=egmlnx02.egm1.esquel.com) (port=1521))
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=IPC) (KEY=EXTPROC0))
Tns-12541:tns:no Listener
Tns-12560:tns:protocol Adapter Error
Tns-00511:no Listener
Linux error:2: No such file or directory

Checked the listener profile Listener.ora and found no problem. Google search: This error is related to the Linux hostname and IP configuration, so hurry to check:

[ORACLE@EGMLNX02 admin]$ hostname
EGMLNX02.egm1.esquel.com
[Oracle@egmlnx02 admin]$ More/etc/sysconfig/network
Networking=yes
Hostname=egmlnx02.egm1.esquel.com

The results found that the host name and IP configuration file hosts, do not know whether the system administrator hand or other reasons, in the Hosts file, 127.0.0.1 configuration of a number of EGMLNX02 (should be three), resulting in an Oracle Database listener server to start an error

About the host name and IP configuration file, in general, hosts file for each behavior of a host, each line consists of three parts, each part by the space separated. The lines at the beginning of the # number are described and are not interpreted by the system.
The first part: Network IP address;
Part II: Host name or domain name;
Part III: host name alias;

So modify the Hosts file, and then restart the listening, OK, the file is resolved.