switching $ORACLE_BASE using oraenv in 11g

I recently installed a couple of Oracle 11g on VM. First one was installed
to /u01 but after testing different things I added one more to /u05.
But it does not really matter, the main thing that 11g raised importance
of $ORACLE_BASE variable added it to different places - oraenv script
(you have noticed sentence about oracle base after execution of the script)
and as parameter to init file.

All that means the $ORACLE_BASE should be dependent on
ORACLE_HOME and be saved somewhere. Moreover the script should
change it! But it was not so. Everytime I ran it $ORACLE_BASE left the
same even they based on the same path as $ORACLE_HOME:

[oracle@oel1 bin]$ . oraenv
ORACLE_SID = [db11106] ?
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1 is /u05/app/oracle
[oracle@oel1 bin]$ . oraenv
ORACLE_SID = [db11106] ? db11a
The Oracle base for ORACLE_HOME=/u05/app/oracle/product/11.1.0/db_2 is /u05/app/oracle
[oracle@oel1 bin]$ . oraenv
ORACLE_SID = [db11a] ? db11106
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1 is /u05/app/oracle

Checking the script I found the part that responsible for
oracle base change and comments there:


# Set the value of ORACLE_BASE in the environment. Use the orabase
# executable from the corresponding ORACLE_HOME, since the ORACLE_BASE
# of different ORACLE_HOMEs can be different.
# The return value of orabase will be determined based on the following :
#
# 1. Value of ORACLE_BASE in the environment.
# 2. Get the value of ORACLE_BASE from oraclehomeproperties.xml as
# set in the ORACLE_HOME inventory.



Going further I found that oraclehomeproperties.xml is under
$ORACLE_HOME/inventory/ContentsXML and it contains properties
and one of them is:

...
property name="ORACLE_BASE" val="/u05/app/oracle"
...

(/u01/app/oracle was for the other oracle home)

That's the place where $ORACLE_BASE and $ORACLE_HOME variable
are put together. But the script doesn't switch base if it was already set.
And the reason of it - orabase script ($ORACLE_HOME/bin).
If you have $ORACLE_BASE value set - orabase returns this value.
If not - it gets value from oraclehomeproperties.xml file:

[oracle@oel1 bin]$ . oraenv
-- switched to another home and got wrong $ORACLE_BASE
ORACLE_SID = [db11a] ? db11106
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1 is /u05/app/oracle
-- wrong value
[oracle@oel1 bin]$ echo $ORACLE_BASE
/u05/app/oracle
-- orabase returns wrong value
[oracle@oel1 bin]$ which orabase
/u01/app/oracle/product/11.1.0/db_1/bin/orabase
[oracle@oel1 bin]$ orabase
/u05/app/oracle
-- unset $ORACLE_BASE
[oracle@oel1 bin]$ export ORACLE_BASE=
[oracle@oel1 bin]$ echo $ORACLE_BASE

-- and now orabase returns right value
[oracle@oel1 bin]$ orabase
/u01/app/oracle

Finally I added the "export ORACLE_BASE=" entry before
"ORABASE_EXEC=$ORACLE_HOME/bin/orabase" to null the value that
orabase could accomodated the real value of $ORACLE_BASE variable.

[oracle@oel1 bin]$ vi /u01/app/oracle/product/11.1.0/db_1/bin/oraenv
[oracle@oel1 bin]$ vi /u05/app/oracle/product/11.1.0/db_2/bin/oraenv
[oracle@oel1 bin]$ . oraenv
ORACLE_SID = [db11106] ?
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1 is /u01/app/oracle
[oracle@oel1 bin]$ . oraenv
ORACLE_SID = [db11106] ? db11a
The Oracle base for ORACLE_HOME=/u05/app/oracle/product/11.1.0/db_2 is /u05/app/oracle

Have a good day!