How to update CentOS, Ubuntu and Debian version of Linux Cloud Servers

The unsupported operating systems versions will no longer receive security updates. If keeping the outdated version, some unauthorized people may target those outdated operating systems because of their vulnerability, allowing them to breach the server and gain personal information. The best possible way to prevent them is to update your operating system to the latest version regularly.

The below steps can be followed to update the version for CentOS, Ubuntu & Debian.

*Please make sure to take proper backup of your entire server before performing the OS upgrade.

CentOS

The below general steps can be used to update the upgrade CentOS 7 to CentOS 8.

1. Check the current CentOS version in the server using the following command.

   # cat /etc/redhat-release
   

2. Once checked, then need to install EPEL Repository in the server.

   # yum install epel-release -y
   

   

3. Install yum-utils in the server.

   # yum install yum-utils
   

   

4. Then need to resolve RPM packages in the server.

   # yum install rpmconf
   AND
   # rpmconf -a
   

   

   

5. Install dnf in the server, dnf is the default package manager for CentOS 8.

   # yum install dnf
   

   

6. Remove the yum package manager from the server.

   # dnf -y remove yum yum-metadata-parser
   AND
   # rm -Rf /etc/yum
   

   

   

7. Upgrading CentOS 7 to CentOS 8.

   # dnf upgrade
   

   

8. Install CentOS 8 release packages on the server.

   # dnf -y upgrade http://mirror.bytemark.co.uk/centos/8/BaseOS/x86_64/os/Packages/centos-release-8.0-0.1905.0.9.el8.x86_64.rpm
   

   

9. Remove all the temporary files.

   # dnf clean all
   

   

10. Need to remove the old kernel core of CentOS 7.

    # rpm -e `rpm -q kernel`
    

    

11. Remove conflicting packages.

    # rpm -e --nodeps sysvinit-tools
    

    

12. Launch the CentOS 8system upgrade as shown.

    # dnf -y --releasever=8 --allowerasing --setopt=deltarpm=false distro-sync
    

    

    

13. Install new Kernel Core for CentOS 8.

    # dnf -y install kernel-core
    

    

14. Install minimal package for CentOS 8.

    # dnf -y groupupdate "Core" "Minimal Install"
    

    

15. All the steps done. Now you can check the CentOS version in the server.

    # cat /etc/redhat-release
    

    

Ubuntu & Debian

1. To check the current OS version in the server.

   # cat /etc/issue
   

   

2. Upgrade the installed packages of Ubuntu version 16.04.

   # sudo apt-get update && sudo apt-get upgrade
   

   

   

3. Install ubuntu update manager.

   # sudo apt install update-manager-core
   

   

4. Start to upgrade Ubuntu server.

   # sudo do-release-upgrade
   

   

   

   

   Enter Y to continue.

   

   Once this done, need a system reboot. Enter Y to restart the server.

5. Now you can check the OS version in the server.

   # cat /etc/issue