Oracle cannot connect troubleshooting [TNS-12541:TNS: No listener]

1. Situation: After the installation of Oracle good, the holiday shutdown after the restart unexpectedly found that can not be normal connection, customer error: Tns-12541:tns: no monitoring program

2. Check:
1. Oracle on the server is up and running
2. Using the Tnsping check, it is found that using "tnsping configuration Name" on the server returns to normal, while using "Tnsping IP" returns a failure.
Suspect: 1521 not open? Use: netstat-a-n | grep 1521 Discovery Port is open normally
3. Solution: Baidu Search all kinds of situations, the final discovery is: Listener.ora in the host must be the computer name, the original configuration file is: localhost, modified after the restart monitoring can be
The following red text for the modified place.

LISTENER =
(Description_list =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC) (KEY = EXTPROC1521))
(ADDRESS = (PROTOCOL = TCP) (HOST = mycomputername) (PORT = 1521))
)
)

-------------------

Linux operation is still not very familiar, the above looks simple, in the Linux operation of various commands, have been located in Baidu ...
Record the following:
Get Computer Name: hostname

Check that the port is open:
1. Telnet IP Port

2. Netstat-a-N | grep 1521

After root login su Oracle cannot use Oracle tools such as Sqlplus because it does not have access to Oracle's environment variables ($ORACLE _home, etc.).
Process one:
Su Oracle Post CD ~
More. Profile view Oracle's environment variables,
Go back to root and add the Oracle configuration in Oracle's. Profile to/etc/profile, then: source/etc/profile
Once again, SU Oracle can use Oracle Tools
Processing two: It is recommended to use Oracle Wired Linux directly, simple and direct

Oracle cannot connect troubleshooting [TNS-12541:TNS: No listener]