Upgrading a system is essential to staying updated in modern technologies to use new features. On 24 September 2019, CentOS officially released CentOS version 8.0, and everyone started looking to upgrade their system from CentOS 7 to 8. CentOS offers multiple features and newly developed software support, so it is good to go for the CentOS 8 instead of CentOS 7. If you are also looking to get the upgrade done in the smoothest way possible, you're in the right place. Read the complete article and get acquainted with the step-by-step approach.

System Requirements and Features of CentOS 8 

CentOS 8 build release is available for: 

  • ppc64le (Little Endian)
  • x86_64
  • aarch64 (ARM 64, ARMv8)

CentOS 8 offers multiple features that create a significant difference between CentOS 7 and CentOS 8. So these features are:

  • There is a default cockpit available now.
  • CentOS 8 offers the latest version of YUM, and it is based on the DNF.
  • CentOS 8 supports 4PB physical memory.
  • It has Python 3.6 as a default version of python.
  • CentOS 8 consists of PHP 7.2 and Nginx 1.14
  • In CentOS, iptables are replaced by nftables as a default framework for network filtering.
  • Contents of CentOS 8 are available by two different repositories, Application Stream and BaseOS.
  • In CentOS, Wayland is a default display server that replaces the Xorg server. 

How to Upgrade Centos 7 to 8?

This upgrade procedure requires the installation of the EPEL Repository, so execute the below command to start the installation process:

# yum install epel-release -y 

You will get a result as shown below!

[root@centos7-PCNAME:~]# yum install epel-release - y
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
* base: centos. mirrors. estointernet.in
* elrepo: mirror.imt-systems.com
* extras: mirrors. piconets. webwerks. in
* updates: mirrors . piconets. webwerks.in
Resolving Dependencies
--->Running transaction check
---> Package epel-release. noarch O: 7—11 will be installed
--->Finished Dependency Resolution
Dependencies Resolved
===================================================================
Package Arch version
===================================================================
Installing: noarch 7—11 
epel-release
Transaction Summary
===================================================================
Install 1 Package
Total download size: 15k
Installed size: 24k
Downloading packages:
No Presto metadata available for extras 
epe1-release-7-1 1 . noarch. rpm
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing: epel-release-7-1 1 . noarch
Verifying: epel-release-7-1 1 . noarch
Installed:
epel-release-7-1 1 . noarch
Complete !
[root@centos7-PCNAME:~]# 

After the successful installation of EPEL, execute the below command for installing the yum utility package (this will also run the yum update to update the repository).

# yum install yum-utils

Once you install the yum-utils in the system, execute the following commands for resolving RPM packages.

 # yum install rpmconf

# rpmconf -a 

Now clean all of the unnecessary files from the system by executing the commands below: 

# package-cleanup --leaves

# package-cleanup --orphans 

After running the cleanup commands, you will get the result below!

[root@centos7-PCNAME:~]# package-cleanup --leaves
Loaded plugins: fastestmirror, langpacks
NetworkManager- libreswan-gnome-1 . 2. G-2. e17. x86-64
djvulibre-devel -3.5.25.3-14. xas_su
giflib-devel-u. 1.6-9. e17.xas_6L,
i bus-libpinyin—l . S. 91-4 .e17. x86-64
libXfont-1.5.G-1.e17. x86-64
libXt-devel-1. 1.5-3. e17. x86-64
libb10ckdev-nvdimm-2. 18-3. e17. x86-64
liberation-serif-fonts—I . 07.2- IS . e17. noarch
libproxy-mozås-O.G. 11—11.e17. x86-64
libreport-anaconda-2. 1. 1 1-42. e17. centos . x86-64
libreport-p1ugin-mai1x-2. 1. 1 1-142. e17. centos. x86-64
libreport-rhe1-anaconda-bugzilla-2. 1. 1 1-42. e17. centos. x86-64
librsvg2-devel-2. GO. 20-1 . e17. x86-64
libsane-hpaio-3. 15.9-3. e17. x86-64
3-27.
lib time zone map-O . . . e17. x86-64
1 . 2-2. e17. xas_su
Iibuser-python- 0. 60-9. e17 . x86-64
libxslt-devel-l. 1 .28-5 . e17.xas_6L,
mesa-libGLES-
python-ntp1ib-O.3.2—1 . e17 . noarch . x86-64 
package-cleanup
[root@centos7-PCNAME:~]# package - cleanup -- orphans
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
* base: centos. mirrors. estointernet.in
* elrepo: mirror.imt-systems.com
* epel: repos . del.extreme-ix.org
* extras: mirrors. piconets. webwerks.in
* updates: mirrors . piconets. webwerks.in
NetworkManager 12. o-a.e17_6. x86-64
NetworkManager -adsl-l. 12 . o-a.e17_6. x86-64
NetworkManager -bluetooth-I. 12. o-a.e17_6. x86-64
NetworkManager -glib-I. 12. o-a.e17_6. x86-64
NetworkManager -libnm-l. 12. o-a.e17_6. x86-64
NetworkManager -ppp-l. 12. o-a.e17_6. x86-64
NetworkManager -team-I. 12. o-a.e17_6. x86-64

After cleaning the system, install the DNF in CentOS 7 because DNF is CentOS 8's default package manager; execute the below command to upgrade CentOS:

# yum install dnf

Do you want to learn more about the Linux commands? Have a go through our complete guide to Linux commands.

The installation will start, and you will get a result as shown:

[root@centos7-PCNAME:~]# yum install dnf -y
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
base: centos.mirrors.estointernet.in
elrepo: mirror.imt-systems.com
epel: repos.del.extreme-ix.org
extras: mirrors.piconets.webwerks.in
updates: mirrors.piconets.webwerks.in
Resolving Dependencies
--> Running transaction check
---> Package dnf.noarch 0:4.0.9.2-1.e17_6 will he installed
--> Processing Dependency: python2-dnf = 4.0.9.2-1.e17_6 for package: dnf-4.0.9.2-1.e17_6.noarch
--> Running transaction check
---> Package python2-dnf.noarch 0:4.0.9.2-1.e17_6 will be installed
--> Processing Dependency: dnf-data = 4.0.9.2-1.e17_6 for package: python2-dnf-4.0.9.2-1.e17_6.noarch --> Processing Dependency: python2-lihdnf >= 0.22.5 for package: python2-dnf-4.0.9.2-1.e17_6.noarch
 --> Processing Dependency: python2-libcomps >= 0.1.8 for package: python2-dnf-4.0.9.2-1.e17_6.noarch
 --> Processing Dependency: python2-hawkey >= 0.22.5 for package: python2-dnf-4.0.9.2-1.e17_6.noarch --> Processing Dependency: libmodulemd >= 1.4.0 for package: python2-dnf-4.0.9.2-1.e17_6.noarch
--> Processing Dependency: python2-lihdnf for package: python2-dnf-4.0.9.2-1.e17_6.noarch
--> Running transaction check
---> Package dnf-data.noarch 0:4.0.9.2-1.e17_6 will be installed
---> Package libmodulemd.x86_64 0:1.6.3-1.e17 will be installed
--> Processing Dependency: libyam1-0.so.20(64bit) for package: libmodulemd-1.6.3-1.e17.x86_64
---> Package python2-hawkey.x86_64 0:0.22.5-1.e17_6 will be installed

Now, remove the yum package manager from the system using the following commands in the terminal:

# dnf -y remove yum yum-metadata-parser

# rm -Rf /etc/yum  

Your system is now completely ready for the CentOS update. Therefore, use the DNF package manager to upgrade the system, so execute the following CentOS update command:

# dnf upgrade

After that, install the CentOS 8 package using DNF by executing the below command (this execution will take a bit of time).  

# dnf install http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-linux-repos-8-2.el8.noarch.rpm  http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-linux-release-8.3-1.2011.el8.noarch.rpm http://mirror.centos.org/centos/8/BaseOS/x86_64/os/Packages/centos-gpg-keys-8-2.el8.noarch.rpm

Now, upgrade your EPEL repository by executing the below command in the terminal: 

dnf -y upgrade https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

Once the EPEL repository successfully upgrades, you can remove all of the temporary files from the system.

# dnf clean all

Now, you can remove the old kernel core of CentOS 7 using this command:

 # rpm -e `rpm -q kernel`

Also, use the below command for removing conflicting packages.

 # rpm -e --nodeps sysvinit-tools

At last, launch the CentOS 8 using the following command:

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

Don't forget to install a new Kernel Core for your CentOS 8 system, so run the below command for installing this Kernel:

# dnf -y install kernel-core 

Now, you can install the minimal packages of CentOS by executing this command:

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

Finally, check the version of your CentOS by executing this command:

# cat /etc/redhat-release

If this command does not work, you can check our previous article on how to find the Linux version. 

Thus, you can easily update CentOS 7 to CentOS 8 without trouble. However, completing this process by following every step carefully is essential, or you will face errors and serious software-related issues.

Conclusion

In this article, we have covered the easiest and most effective procedure on how to upgrade CentOS 7 to 8. As we have mentioned previously, CentOS 8 was released and consisted of multiple features and newly developed software support.

Hence, you can go for CentOS 8 instead of CentOS 7 to use new features in your system. CentOS 8 requires a particular specification for appropriate working, so ensure your system fulfils all of the requirements to easily update your CentOS repositories. 

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