How do I know if a listener is running?

Do the following:

1. Log on to the host where the Oracle database resides.
2. Change to the following directory: Solaris: Oracle_HOME/bin. Windows: Oracle_HOME\bin.
3. To start the listener service, type the following command: Solaris: lsnrctl START. Windows: LSNRCTL. …
4. Repeat step 3 to verify that the TNS listener is running.