====== Centos OS 7 + Oracle XE 21c Instructions of Installation ======

**How to create a virtual machine (VM) with the Centos OS 7 template**

Select, mark or enter:
  - **VM Name** - //create your VM name //;
  - **Hold** - check the box;
  - **Memory** - 4 GB;
  - **CPU** - 2
  - **VCPU** - 4
  - **centos7** - 20 GB

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Open the virtual machine which you created:
  - Add //1521// to **TCP_PORT_FORWARDING 22**;
  - Expand the 5th function selection icon in the top menu bar on the right, and press **Release**;
  - Wait for it to load.

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Launch the **Putty** app and add your private key. 
More about **Putty** and private keys read ****[[en:duk:ssh_key|here]]****

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Copy the login credentials from the server control panel //CONNECT_INFO1//. In **Putty** app enter the SSH key keyword as shown in the example and press **Open**.

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On the command line, write the commands in order. Sometimes you will need to press **"y "**. You must wait until the command you have previously typed has been executed before typing another command.

<code>
  sudo yum check-update
  sudo yum update
  sudo yum localinstall https://drive.mif.vu.lt/s/T4Z9WxzDgoDqoey/download/oracle-database-preinstall-21c-1.0-1.el7.x86_64.rpm
  sudo yum localinstall https://drive.mif.vu.lt/s/swmrJSjMsfjP5Ax/download/oracle-database-xe-21c-1.0-1.ol7.x86_64.rpm
</code>

After the installation, which may take some time, you need to enter the configuration command, set the password and wait for the configuration to finish.
<code>sudo /etc/init.d/oracle-xe-21c configure</code>

**How to connect to the Oracle database**

Register and download [[https://www.oracle.com/tools/downloads/sqldev-downloads.html | SQL DEVELOPER]]. Unzip the files and run the application.

At the top right with the right mouse button, click on **Oracle Connections** and select **New Connection**. In the window that appears, in the appropriate fields, type:

  - **Name** - session title.
  - **Username** - the first time you log in, the SYSTEM user is active, others can be created later.
  - **Password** - the one you set during installation.
  - **Hostname** - the external IP address that has been assigned. {{ :cloud:oracle_6.png }}
  - **Port** - port attributed by the //OPEN NEBULA//. You will find it in the main server panel, next to the **1521** you entered.

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**NOTE**: If no new users can be created, enter ''alter session set "_ORACLE_SCRIPT"=true;''