Linux oraenv Tips

Linux for the Oracle DBA -Customizing the Oracle User's Environment

There are many ways to customize the Oracle user on the system.  I strongly recommend making the changes covered in this section.  Also see my notes on oratab.

To effectively administer the Oracle installation we that was just made, it is useful to have several environment variables set whenever a command line session is started.  The Oracle provided script oraenv is the best way to set these variables automatically. The oraenv scriptis installed in /usr/local/bin and takes values from the oratab file located in /etc.  The oratab filetypically contains an entry for each database, but in the current configuration, there is no database set up.  To use the oraenv script, set up a dummy entry in the oratab file.

The oratab file can be edited by the oracle user using vi or another text editor.  Each line in the oratab file has three elements separated by colons.  The first element is the SID, the second indicates the Oracle Home directory for that SID, and the third indicates if the database should be started and stopped by the dbstart/dbshut commands.

Edit the oratab file and add the following line:

db_11g:/u01/app/oracle/product/11.1.0/db_1:N

Though a database does not exist by the name db_11g, this entry allows us to setting up the environment for this home without having to set several variables manually.  Make sure the final element is set to N so Oracle does not attempt to start a database that is not there.

With an entry now in the oratab file, use the oraenv command to set up theour environment.  To do that, run .oraenv which causes the oraenv script to be run as part of the current shell rather than as a subprogram.

$ . oraenv
 
ORACLE_SID = [oracle] - db_11g
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1
is /u01/app/oracle
 
$ echo $ORACLE_SID
 
db_11g
 
$ echo $ORACLE_HOME
 
/u01/app/oracle/product/11.1.0/db_1
 
$ echo $PATH
 
/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/home/oracle/bin:/u01/app/
oracle/product/11.1.0/db_1/bin
 
Among other things, the oraenv script sets the ORACLE_SID and
ORACLE_HOME variables.  The PATH variable is also updated to include
the location of the Oracle binaries. Though they could be set
manually, the oraenv script is the best way to set these variables. 
Since these variables should be set anytime, log in as oracle and
can then add the oraenv command to the user's profile.

A user's profile, often referred to as the dot-profile, is a
hidden file in their home directory that is executed when a user
logs in. Since Linux uses the bash shell
by default, the profile file is called .bash_profile.  Using the -a
option, it can be seen in an ls listing.

$ pwd
 
/home/oracle
 
$ ls -a
 
.              .bash_logout   database_11g  .gconfd          .mozilla
..             .bash_profile  .emacs        .gnome2          .viminfo
.bash_history  .bashrc        .gconf        .gnome2_private  .Xauthority
 
The profile can be edited with vi or another text editor.  To run
oraenv when the user
logs in, add the following lines to the .bash_profile file.

ORACLE_SID=db_11g
ORAENV_ASK=NO
. oraenv

This causes the Oracle variables to be set based on the oratab
entry for db_11g without any prompting.  If the variable ORAENV_ASK
is changed to YES or is not set at all, there is a prompted to enter
a SID when logging in.

Calling the oraenv File

The oraenv scriptshould be
called from a user's .bash_profile
to make these configuration changes.  It is typically installed in
the /usr/local/bin directory and as long as that is included in
the PATH variable, it can be called with the following syntax.

. oraenv

If the ORACLE_SIDvariable
is set before the oraenv script is run, the value of ORACLE_SID is
given as a default when the user is prompted to enter a SID. 
Additionally, if the ORAENV_ASK variable is set to NO before
oraenv is called, then oraenv does not prompt for a SID to be
entered; instead, the value from ORACLE_SID is used.  Below is a
script showing oraenv being called without being prompted to enter
a SID.

export
ORACLE_SID=TEST
export ORAENV_ASK=NO
. oraenv

These are both valid methods for calling the oraenv
script.  Which one you choose will depend on if you wish a user to
be prompted to give a SID when they log in.

Adding Custom Code to the oraenv File

Sometimes it is necessary to have product-specific environment
settings for a product associated with a given Oracle database. 
The end of the oraenv script
has a special section to accommodate this kind of setting.

Custom settings can be added to the oraenv script after the
comment reading 'Install any 'custom'?? code here'.  The oraenv
script is a Bourne shell script - most common shell scripting
syntax will work.  Here is a short example of custom code added to
the oraenv script:

...
#
# Install any "custom" code here
#
 
TEMP_DIR=/tmp
export TEMP_DIR
 
case $ORACLE_SID in
    TEST)
           SCRIPT_DIR=/u01/app/laftdba/test
           export SCRIPT_DIR
    ;;
    PROD)
           SCRIPT_DIR=/u01/app/laftdba/prod
           export SCRIPT_DIR
    ;;
    *)
           unset SCRIPT_DIR;
    ;;
esac

In the example above, the first two lines setting
and exporting the variable TEMP_DIR are run for any database.  The
case statement then executes additional code based on the setting
of ORACLE_SID.  case statements will be explained further in the
section on shell scripting.

Oracle-Specific Environment
Settings

Oracle provides the oraenv script to set up most environment
variables necessary for Oracle administration.  The oraenv script
sets the ORACLE_HOME, ORACLE_BASE and LD_LIBRARY_PATH variables
and updates the PATH variable with Oracle specific values.

WARNING: When
setting up accounts which will be accessed from other
systems through scripts, avoid having the user prompted to
enter a SID.

Conclusion

There are a lot of steps to getting a system ready for Oracle. 
System requirements, installed software and many settings must all
be correct or Oracle will not function properly.  As these steps are
reviewed, it is a good idea to take notes on what things were set to
when they were found and what changes were made to prepare for
Oracle.  This will make preparing future systems much easier.

The next chapter, we will start to explore the many things we
that can be done to further customize and tune the Linux system.