USING TWO_TASK, LOCAL, AND ORACLE_SID WHEN INSTALLING ORACLE APPLICATIONS (Doc ID 1020395.102)

Problem Description
-------------------
 
You are installing Release 11 Oracle Applications and are reading Oracle
Applications Installation Release 11 for UNIX manual on page 2-10, step 13.
The manual says to "verify $ORACLE_HOME, $ORACLE_SID, and $TWO_TASK."  
You are looking for an explanation on the difference between specifying 
$ORACLE_SID and $TWO_TASK. 
 

Problem Explanation
-------------------

Depending on where the database server will be located in relation to the
Oracle Applications, $ORACLE_SID and $TWO_TASK need to be set correctly.  
Otherwise, installation utilities such as ADAIMGR (Autoinstall) will fail due 
to failed connections to the database.


Solution Description
--------------------

If you are connecting or using a database on the same machine and the 
database exists at where the $ORACLE_HOME environment variable points to,
then specify $ORACLE_SID.

Specify $TWO_TASK if you are connecting to a database that exists on another
machine or if you have a server-partitioned installation (database exists 
on the same machine, but at a location other than where $ORACLE_HOME points to).
You should also specify $ORACLE_SID, but it will be treated as a comment and 
the value will not be used.
 

Solution Explanation
--------------------
 
Specifying $ORACLE_SID causes all Applications utilities to use the oracle
executable that exists in $ORACLE_HOME.  If the database does not exist at the
location, the connection will not be made and the process will fail.  This 
method is only possible when database exists on the same machine.

Specifying $TWO_TASK causes all Applications utilities to use the value
of $TWO_TASK and use it as a SQLNET connect string.  Therefore, if your database
exists on a different machine and must go through SQLNET to connect to it,
it is required that you specify $TWO_TASK.  The same holds true if you will be
installing Oracle Applications using Server-Partitioning.  In this case, the 
Oracle database does not exist at the location where $ORACLE_HOME points
to.  Therefore, the connection must go through SQLNET.  This configuration
requires the use of $TWO_TASK.

If you specify both $ORACLE_SID and $TWO_TASK, $TWO_TASK will take precedence.
Therefore, if everything is located on one machine, you need not set the 
$TWO_TASK environment variable.  Use "unset $TWO_TASK" command to remove the
variable completely.  Do not set the value to null.  Setting the value to null
will cause ad utilities to core dump when executed.