For many, many years we’ve been clouding up the oracle user’s .bashrc and .bash_profile scripts with ‘lots of things’. Some of these things will be set automatically when we run the . oraenv command (that’s dot space oraenv). Our good old friend LD_LIBRARY_PATH gets set automatically, ORACLE_HOME gets set automatically, and the PATH is extended to search in your ORACLE_HOME/bin directory.
The below screenshot comes from a ‘new’ Oracle Linux 6 system where I’ve done a software only install of Oracle Database 126.96.36.199 and have yet to create any databases. Because I don’t have a database yet, I have to type in the path to the ORACLE_HOME when I give some random SID. Once I have a database created, that database will get added to the /etc/oratab file and the SID will be recognized and automatically set the ORACLE_HOME for me.
Click the image above to get a full size picture of what’s happening.
Based on the above, I might change things a bit in this post from my 12c Install Series.