Found usually in /etc or /var/opt/oracle.
oratab is used by ORACLE utilities. It is created by the root.sh script (a part of Oracle installer), and is updated by the Database Configuration Assistant when creating a database.
Entries in this file have the following format:
A colon, ':', is used as the field terminator. A new line terminates the entry. Lines beginning with a pound sign, '#', are comments.
The first and second fields are the system identifier and home directory of the database respectively. The third filed indicates to the dbstart utility that the database should , "Y", or should not, "N", be brought up at system boot time.
List all installed Oracle products
For Oracle 8i and above:
Verify Oracle installation
select host_name, instance_name, version, status from v$instance;
TNS-12542: TNS:address already in use
Check if the TNS port is not already in use by another Oracle instance.
- Check if the host name specified in listener.ora is correct.
- Do a netstat - a to check if any other application is using the port specified in listener.ora
- If the listener.ora has been copied from somewhere (samples or elsewhere), check the ORACLE_HOME
Set the Listener Process for Automatic Startup
Edit /var/opt/oracle/lsnrtab, and change/add a line containing the name of your listener (as specified in listener.ora and change the start-up value to "Y")