How to delete Oracle instance under Linux system

Oracle is a widely used relational database management system, and many companies use Oracle to manage their data. Under certain circumstances, you may need to remove an Oracle instance, such as if you need to reinstall Oracle or if you need to move the instance from one server to another. This article will introduce how to delete an Oracle instance under Linux system.

1. Stop the Oracle instance and listener

Before deleting the Oracle instance, you need to stop the running instance and listener. You can use the following command to stop the Oracle instance and listener:

$ORACLE_HOME/bin/sqlplus /nolog

SQL> connect / as sysdba

SQL> shutdown immediate

SQL> exit

$ORACLE_HOME/bin/lsnrctl stop

2. Uninstall related software packages

Before deleting the Oracle instance, you need to uninstall the Oracle-related software packages . Packages can be uninstalled using the following commands:

# rpm -e --nodeps oracle-validated
# rpm -e --nodeps oracle-database-server-12cR2-preinstall

These commands will uninstall packages that are automatically installed during Oracle installation, but please note that you only need to uninstall these packages if you have installed them first. If they are not installed then you can skip this step.

3. Delete instance files and directories

To delete an Oracle instance, you need to delete the files and directories that were automatically created when you installed Oracle. Here are the files and directories you need to delete:

• $ORACLE_HOME: This is Oracle's home directory and the primary location for instance files and directories.
• /etc/oratab: This is a configuration file that contains all Oracle instances.
• /etc/init.d/oracle: This is a directory that contains the Oracle startup script.
• $ORACLE_BASE: This is the base directory that contains your Oracle instance.
• $ORACLE_HOME/oradiag_*: This is the directory that contains diagnostic information for the Oracle instance.

You can use the following command to delete instance files and directories:

rm -rf $ORACLE_HOME
rm -f /etc/oratab
rm -rf /etc/init.d/oracle
rm -rf $ORACLE_BASE
rm -rf $ORACLE_HOME/oradiag_*

4. Delete Oracle users and groups

After deleting the Oracle instance, You also need to delete the Oracle users and groups. Oracle users and groups can be deleted using the following commands:

userdel -r oracle
groupdel dba

These commands will delete Oracle users and groups along with their home directories and files.

In short, Oracle is a very powerful and widely used database management system. In some cases, you may need to delete the Oracle instance. In this article, we describe how to delete an Oracle instance under Linux systems, including stopping the instance and listeners, uninstalling related packages, deleting instance files and directories, and deleting Oracle users and groups. Hope this article can be helpful to you!

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