Linux系统中，启动Oracle监听的时候报如下错误：
[oracle@CentOS ~]$ lsnrctl start
LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 17-APR-2010 00:25:22
Copyright (c) 1991, 2005, Oracle. All rights reserved.
Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
TNS-12537: TNS:connection closed
TNS-12560: TNS:protocol adapter error
TNS-00507: Connection closed
Linux Error: 29: Illegal seek
经过检查，发现hosts文件，内容如下：
[root@centos ~]# cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
::1 localhost.localdomain localhost
192.168.19.219 centos
缺少了 127.0.0.1 localhost行，加上这行后，如下所示，监听就可以正常启动了。
[root@centos ~]# cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
::1 localhost.localdomain localhost
127.0.0.1 localhost
192.168.19.219 centos