Oracle is very popular database which is used by big enterprises, banks, governments etc. Oracle Database provides a lot of useful features to the MS SQL, PostgreSQL, MySQL etc. Oracle Express is lightweight database server provided by Oracle. We can use Oracle Express Edition without a fee. Oracle Express Edition is named as Oracle XE .
Download
Oracle can be installed into Linux and Unix based operating systems. It is provided as 64 bit application architecture. We will download Oracle Express Edition from following URL.
We can use following URL to download Oracle Express Edition RPM package which can be installed on CentOS, Fedora, RedHat
http://download.oracle.com/otn/linux/oracle18c/xe/oracle-database-xe-18c-1.0-1.x86_64.rpm
Install Prerequisites Package oracle-database-preinstall-18c
We will use rpm command in order to install the downloaded package. Before installing package we need to install prerequisites which is required by the package. The prerequisites are provided by the oracle-database-preinstall-18c package.
First we will download preinstallpackage. This package can be used for CentOS 7 , RedHat 7 , Oracle Linux 7 and sub versions.
$ curl -o oracle-database-preinstall-18c-1.0-1.el7.x86_64.rpm https://yum.oracle.com/repo/OracleLinux/OL7/latest/x86_64/getPackage/oracle-database-preinstall-18c-1.0-1.el7.x86_64.rpm
Then we will install package with the following command.
$ sudo yum -y localinstall oracle-database-preinstall-18c-1.0-1.el7.x86_64.rpm
Install with rpm Command
We will use rpm command with -i option and provide the package name. If the package is different then current working path we should provide the full path.
$ sudo rpm -i oracle-database-xe-18c-1.0-1.x86_64.rpm
Initialize and Configure Database
We will use oracle-xe-18c script in order to configure and initialize the database . We will use default configuration which can be found /etc/sysconfig/oracle-xe-18c.conf .
$ sudo /etc/init.d/oracle-xe-18c configure
We can see that we will provide root privileges with sudo command. After that we will provide the password we want to use for SYS, SYSTEM and PDBADMIN accounts. In order to make database more secure use at least 8 character, uppercase,special characters in password. Following will be a secure password.
q323+F^Q_?qwe.321
Initialization Phases
During the initialization following phases will be completed in row.
- Set Password
- Create Users
- Prepare Database engine
- Copy Database Files
- Create Oracle Instance
- Start Oracle Instance
Installation Logs
Oracle is very detailed and complex database server. Event during installation a lot of log and log files are created about the installation and usage. We can list these log files from /opt/oracle/cfgtoollogs/dbca/XE/ .
$ cd /opt/oracle/cfgtoollogs/dbca/XE/ $ ls
In this example we will list basic installation log which is stored in XE.log file.
$ less XE.log
Connection Strings
In order to use Oracle database from different applications we need to use Connection Strings . This connection string provides connection information to the Oracle Database.
Pluggable database: localhost.localdomain/XEPDB1 Multitenant container database: localhost.localdomain
Oracle Enterprise Manager or Web Based Management
Oracle Enterprise Manager is a web based Oracle database management tool. We can use this tool from browser by navigating following URL. It uses port 5500 . But notice that it requires Adobe Flash which may not enabled or installed in your browser.
https://localhost:5500/em/login
Check Oracle Listener Service
We can check Oracle Listener Service with the ps command. We will filter processes which names contains tnslsnr .
$ ps -ef | grep tnslsnr
