How to upgrade ubuntu server from Ubuntu 16.04 to Ubuntu 18.04

Ubuntu 16.04 LTS becomes EOL on Apr 2021. Ubuntu supports upgrade from one LTS to the next LTS in sequential order. To upgrade a server system follow the below steps. 

• Confirm OS version is Ubuntu 16.04 using command lsb_release –a 

• Update all the software packages repository list and upgrade packages on the existing system using the below command. It's recommended to reboot the system after all updates are applied. 

            sudo apt-get update

            sudo apt-get upgrade -y

            sudo apt-get dist-upgrade -y

• Install the Ubuntu Update Manager using the below command.

                    sudo apt-get install update-manager-core

• Make sure the Prompt line in /etc/update-manager/release-upgrades is set to 'lts' if you only want LTS upgrades.

• Upgrading to Ubuntu 18.04. To begin this process run the following command:

            sudo do-release-upgrade

• Before making any changes the above command will first verify whether the system is ready to update or not. The user will get prompted with information about the upgrade. Press Y to continue.
• After you enter the upgrade command, you will be asked to confirm that you want to update via SSH. Type Y to continue.

• Now Ubuntu will check for the packages that need the update and gives the information about the packages which will be added, removed, and the size of the update.

• The up-gradation process will take some time. During the up-gradation process, you may receive a prompt that will require your input. Kindly select a suitable option for you. You will have to select whether you want to install the new version of the file and overwrite the changes, keep the currently installed version, or merge the files.

• During the upgrade, it will ask to remove obsolete software Press Y to continue.

• After completion of the upgrade process, a system restart will be required.

• Post restart you may verify the Ubuntu version using lsb_release –a. 

KB: https://ubuntu.com/server/docs/upgrade-introduction

How to install CentOS 7

CentOS media is available on centos.org. Please watch the below video to install CentOS 7.

How to set a Static IP Address on CentOS-7

When you install the CentOS, IP Address set to dhcp mode. The configuration file for the network interfaces located at directory /etc/sysconfig/network-scripts. 

To list the network interfaces you need to type the following command:

~]$ ip a

DHCP Configuration for ens33 stored in file ifcfg-ens33 and the same is located at directory /etc/sysconfig/network-scripts/. It's look like below.

TYPE=Ethernet

PROXY_METHOD=none

BROWSER_ONLY=no

BOOTPROTO=dhcp

DEFROUTE=yes

IPV4_FAILURE_FATAL=no

NAME=ens33

UUID=d28f4e88-c167-4b78-b918-7b6e55c775e2

DEVICE=ens33

ONBOOT=yes

There are two method to Configure static IP address on ens33.

Method 1 : 

To configure a static IP address on ens33 using ifcfg file, edit file ens33-ifcfg using vi editor. File ens33-ifcfg is located at directory /etc/sysconfig/network-scripts/

~]$ vi /etc/sysconfig/network-scripts/ifcfg-ens33

Update file ifcfg-ens33 as per below

TYPE=Ethernet

PROXY_METHOD=none

BROWSER_ONLY=no

BOOTPROTO=none

DEFROUTE=yes

IPV4_FAILURE_FATAL=no

NAME=ens33

UUID=d28f4e88-c167-4b78-b918-7b6e55c775e2

DEVICE=ens33

ONBOOT=yes

IPADDR=172.16.16.2

PREFIX=16

GATEWAY=172.16.16.1

DNS1=8.8.8.8

Save and closed the file. Static IP Address configuration will be applied after network service restart or manually making interface down and up. You may use below command for network service restart.

~]$ systemctl restart network

To down and up network interface use below command

~]$ ifdown ens33

~]$ ifup ens33

Method 2 :

You may also configure static IP Address using NetworkManager text user interface (TUI) tool. nmtui, provides a text interface to configure networking by controlling NetworkManager.

If  NetworkManager-tui is not install, issue the following command as root:

~]# yum install NetworkManager-tui

To start nmtui, issue a command as follows:

~]$ nmtui

after using nmtui command, The text user interface appears. To navigate, use the arrow keys or press Tab to step forwards and press Shift+Tab to step back through the options. Press Enter to select an option and use Space bar toggles the status of a check box.

To set static IP address on ens33 using nmtui use below command.

~]$ nmtui edit ens33

Below windows will be open after above command