监听lsnrctl status查询状态报错linux error 111:connection refused

报错现象
今天给客户一个单实例环境配置监听，创建正常，查询状态异常报错
tns  tns  tns  linux error :connection refused

匹配MOS
Starting TNS Listener or LSNRCTL Start Yields TNS-, Linux Error: : Connection Refused (文档 ID 343295.1)

>lsnrctl status
Any of the following listener error stacks might be thrown:
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=<hostname>)(PORT=)))
TNS-: TNS:no listener
TNS-: TNS:protocol adapter error
TNS-: No listener
Linux Error: : Connection refused

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC)))
TNS-: TNS:connection closed
TNS-: TNS:protocol adapter error
TNS-: Connection closed

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=<hostname>)(PORT=)))
TNS-: TNS:lost contact
TNS-: TNS:protocol adapter error
TNS-: Lost contact
Linux Error: : Connection reset by peer

CHANGES
This is likely a new installation.
CAUSE
. There is possibly an incorrect IP Address specified for the host in the /etc/hosts file.
For example:
.xxx.yyy.zzz <hostname>.<domain name>
Whereas the actual ip address for the host "<hostname>.<domain name>" is .aaa.bbb.ccc
. Also, the localhost reference may be incorrect or missing from the /etc/hosts file.
. Oracle may not have read access to /etc/nsswitch.conf file.

SOLUTION
To implement the solution, please execute the following steps:
. Correct the mapping in the /etc/hosts file by adding/correcting the IP address and/or hostname reference for the Unix/Linux Server (both long and short host names).
For example:
# Add or edit the /etc/hosts file to include a valid entry for the Server:
.aaa.bbb.ccc <hostname>.<domain name> <hostname>
. Check that the localhost loopback name and address are correct (both long and short host names).
An example of a correct localhost entry would be as follows:
127.0.0.1 localhost.localdomain localhost
. Remember to save the /etc/hosts file and then start the listener.

本次是配置/etc/hosts文件时，未注意直接清空/etc/hosts文件导致Localhost信息丢失，最终导致监听程序无法正常运行

. Check permissions on /etc/nsswitch.conf file to ensure group and other have read access.

- If necessary change permisions on /etc/nsswitch.conf as follows:

chmod  /etc/nsswitch.conf