Monthly Archives: November 2009

hp-ux, linux, unix

String replacement at UNIX or LINUX command prompt

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As an Oracle DBA you will come across many situations where you need to replace string text within OS layer files. This procedure covers the use of Perl command to perform such a task. This procedure will work in both UNIX and LINUX.

1. Logon to you Oracle server as the owner of the files you wish to perform a string replacement on.

2. We will use the command (“perl -pi -e ‘s/{old_string}/{new_string}/g’ {file_name}”) to perform our string replacement.

3. In this example we will replace all of the references to the string “MARS” with the string “EARTH” in any file that ends in test*sh, the command will appear as:

perl -pi -e ‘s/MARS/EARTH/g’ test*sh

4. List all of the contents of files of the format test*sh with the cat command.

mylinux:>cat test*sh
MARS
MARS
MARS
MARS
mylinux:>

5. Execute your perl command in the same directory where your the files are located.

mylinux:>perl -pi -e ‘s/MARS/EARTH/g’ test*sh mylinux:>

6. List all of the contents of the files with format of test*sh with the cat command.

mylinux:>cat test*sh
EARTH
EARTH
EARTH
EARTH
mylinux:>

As you can see above the test string “MARS” has been replaced with “EARTH”. This completes replacement of text string with Perl.

Larry Catt, OCP 9i, 10g
oracle@allcompute.com
www.allcompute.com

hp-ux

Setting the backspace key in HP-UX:

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The following procedure describes the setting of the backspace key in HP-UX

1. Logon to your HP-UX server.

2. While typing a command you make a mistake, but instead of backspacing the system produces ^? marks, as seen below.

myLINUX:> ls -lrt^?^?^?^?^?
ls: illegal option —
ls: illegal option —
ls: illegal option —
ls: illegal option —
ls: illegal option —
usage: ls -1ARadeCxmnlogrtucpFLbqisf [files]
myLINUX:>

3. From the command prompt type the command: stty erase ^?

myLINUX:> stty erase ^?
myLINUX:>

4. Now the backspace key is enabled for this session.

5. To automate this process, place the line command (stty erase ^?) at the end of your .profile file in you home directory. This will enable the backspace operation upon connection.

Larry J. Catt, OCP 9i, 10g
oracle@allcompute.com
www.allcompute.com

11g, audit, Oracle, Oracle 10g, oracle 9i

Auditing the use of an Oracle privilege:

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Oracle provides the ability to audit your database activities on a multitude of level which provides the administrator the ability to find suspicious activity. In this article we will show how to audit use of a system privilege by a particular user in the Oracle RDBMS. This procedure will work on any OS.

1. Logon to your Oracle database server as the Oracle software owner.

2. Logon to SQLPLUS with sysdba privileges.

mylinux:>sqlplus ‘/ as sysdba’

SQL*Plus: Release 10.2.0.4.0 – Production on Sat Nov 14 13:28:31 2009

Copyright (c) 1982, 2007, Oracle. All Rights Reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>

3. Check the current setting of the initialization parameter AUDIT_TRAIL with the command: show parameter {initialization_parameter}
The initialization parameter AUDIT_TRAIL controls auditing at the database level and can be set to three definitions: 1. DB – audit trail in the database; 2. OS – audit trail on the OS; and 3. none – no auditing. In this procedure we want the definition to be set to DB.

SQL> show parameter AUDIT_TRAIL

NAME TYPE VALUE
———————————— ———– ——————————
Audit_trail string DB

SQL>

4. If the parameter is not set to DB and you are using a SPFILE, execute the command: alter system set audit_trail=DB scope=spfile; and bounce the database. If you are using an init file, shutdown the database, add the string AUDIT_TRIAL=DB and start the database.

NOTE: If you do not know if you are using an SPFILE or INIT file, search ORACLE SPFILE vs INIT File

SQL> alter system set audit_trail=DB scope=spfile;

System altered.

SQL>

5. Restart your database if you had to change the audit_trail parameter.

6. In this procedure we will audit the creation of tables by the user LJCATT. To perform this auditing, we will use the command: audit create table by {user_name};

SQL> connect / as sysdba
Connected.
SQL> audit create table by ljcatt;

Audit succeeded.

SQL>

7. Perform a select on the view DBA_PRIV_AUDIT_OPTS, to verify that auditing is enabled.

SQL> select user_name, privilege from dba_priv_audit_opts;

USER_NAME PRIVILEGE
—————————— —————————————-

LJCATT CREATE TABLE

SQL>

8. Logon as the user you are auditing and create a table.

SQL> connect ljcatt
Enter password:
Connected.
SQL> create table test_audit(col_a varchar2(30));

Table created.

SQL>

9. Logon with sysdba privileges and verify that the create table action was recorded in you DBA_AUDIT_TRAIL view. As seen below the audit record for the create table privilege was recorded.

SQL> connect / as sysdba
Connected.
SQL>
SQL> select username, action_name from dba_audit_trail;

USERNAME ACTION_NAM
———- ———-
LJCATT CREATE TABLE

This completes auditing of a system privilege by a user account within the Oracle RDBMS.

Larry J. Catt, OCP 9i, 10g
oracle@allcompute.com
www.allcompute.com

11g, ASM, hp-ux, itanium, linux, Oracle, Oracle 10g, oracle 9i, RAC, SQL, uncategorized, unix

Senior-Level DBA Interview Question:

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With well over a decade of Oracle experience from version 6 to 11g, I have had my share of interviewing prospective DBA employees in a range from Junior to Senior DBAs. Needless to say in this field, technical competence is the key to any new hire and early on I made the blunder of not asking the write questions during the interview. I am sure every senior person or manager has made this mistake and had to deal with either training the person from scratch or letting them go. Either of these options is not desirable in our fast past business world. So, I decided to write a couple of articles which cover what I believe a Junior, Mid, and Senior Oracle DBA should know to fill their prospective positions.

In this article we will cover what a Senior Level DBA should know to be successful. If you have any comments or questions, please email me at larry.catt@relidb.com.

Questions: NOTE: Answers here can be very broad, however they not always wrong. That is why it is important to have a proven DBA on staff or one you can call to review the answers. I have seen very inventive ways to get around the most impossible tasks and while they do not actually meet the standard way of doing the work, I would not count these people out. A person whom thinks outside of the box is very valuable in IT and believe it or not, some of the best DBA’s I have ever met thought completely outside the box, however always accomplished the task.

1. You have a brand new Solaris Machine, freshly built by the SA, with all Oracle RDBMS recommended patching and Kernel Parameters set. Please give the order of tasks to install Oracle up to its latest CPU?

2. You have just moved Oracle Binary files from an ORACLE_HOME on one server to another server. What is the oracle utility command you would use to make this new ORACLE_HOME usable?

3. Tell me why just copying the oracle datafiles from HP-UX to LINUX RHEL and starting the database would not work?

4. In what months does Oracle release CPU patches and what is the utility to apply them.

5. You need to shutdown the oracle database but it will not shutdown with SHUTDOWN IMMEDIATE. How will you shutdown the database?

6. How do you logon to Oracle server without knowing any oracle passwords?

7. How would you determine that SCATTERED READ where occuring?

8. How would you see the SQL of the currently active sessions from a command prompt?

9. When having multiple oracle homes on a single server or client what is the parameter that points all Oracle installs at one TNSNAMES.ORA file.

10. You have ASM database that used by three production systems. The server which the ASM database is shutdown. What happens to the production RDBMS?

Answers:

1. You have a brand new Solaris Machine, freshly built by the SA, with all Oracle RDBMS recommended patching and Kernel Parameters set. Please give the order of tasks to install Oracle up to its latest CPU?

– Verify that all patches are installed and kernel parameters set.(Some not all SA say the system is ready when it is not. You can save yourself a lot of problems by double checking)
– Configuration of .profile or .bash_profile for the Oracle owner.
– Base Installation of Oracle (ie what to get to 10.2.0.4 must install Oracle 10.1 first).
– Upgrade to Oracle Version Desired.
– Upgrade the database(if upgrade is necessary)
– Run UTLRP.SQL.
– Apply lastest CPU patch.
– Run UTLRP.SQL.
– Configuration of Listener.
– Configuration of client TNSNAMES.ORA file.

2. You have just moved Oracle Binary files from an ORACLE_HOME on one server to another server. What is the oracle utility command you would use to make this new ORACLE_HOME usable?

Solution:
Relink all

3. Tell me why just copying the oracle datafiles from HP-UX to LINUX RHEL and starting the database would not work?

Solution:
Differing Indian codes.

4. In what months does Oracle release CPU patches and what is the utility to apply them.

Solution:
JAN, APR, JUL, OCT

5. You need to shutdown the oracle database but it will not shutdown with SHUTDOWN IMMEDIATE. How will you shutdown the database?

Solution:
Kill the smon process.

6. How do you logon to Oracle server without knowing any oracle passwords?

Solution:
Sudo to the Oracle software owners account and logon with the command sqlplus ‘/ as sysdba’

7. How would you determine that SCATTERED READ where?
Solution:

Look in the views v$session_wait or v$session_wait_history.

Could give:

Statspack or EM report.

8. How would you see the SQL of the currently active sessions from a command prompt?

Solution:
Compare tables V$SQL view by sql_address with V$SESSION view of currently active sessions.

9. When having multiple oracle homes on a single server or client what is the parameter that points all Oracle installs at one TNSNAMES.ORA file.

Solution:
TNS_ADMIN

10. You have ASM database that used by three production systems. The server which the ASM database is shutdown. What happens to the production RDBMS?

Solution:
Other database would shutdown abort.

Larry Catt, OCP 9i, 10g
oracle@allcompute.com
www.allcompute.com