Oracle Databases implemented on Unix and Linux have a file /etc/oratab file which determines the current SID, Oracle Homes, or
active status which exist on the server, if a proper installation is done. This procedure uses the file to extract
current ORACLE_HOME(s).

1. Logon to your Oracle Server as the Oracle software owner.

[root@linux2 ~]# su – oracle
Last login: Wed Oct 5 15:16:55 EDT 2016 on pts/2
[oracle@linux2 ~]$

2. Execute the command: egrep -E -v ‘^(#)’ /etc/oratab | awk /./ | awk -F: ‘{print $2}’

[oracle@linux2 ~]$ egrep -E -v ‘^(#)’ /etc/oratab | awk /./ | awk -F: ‘{print $2}’
/opt/app/oracle/product/12.1.0.2/db_1
[oracle@linux2 ~]$

3. For this system there is only one database with a ORACLE_HOME of ‘/opt/app/oracle/product/12.1.0.2/db_1’.

Larry Catt
OCP