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升级centos7到centos8 教程

admin linux服务 2022-07-19 693浏览 0

In this article, you will learn how to upgrade CentOS 7 to CentOS 8.5 release. The steps described herein do not depict the official upgrade and this should not be applied to a production server yet.

Step 1: Install the EPEL Repository

To start off, install the EPL repository by running:

# yum install epel-release -y

Install EPEL Repo in CentOS 7
Install EPEL Repo in CentOS 7

Step 2: Install yum-utils Tools

After successfully installing EPEL, install yum-utils by running the command below.

# yum install yum-utils

Install yum-utils in CentOS 7
Install yum-utils in CentOS 7

Thereafter, you need to resolve RPM packages by executing the command.

# yum install rpmconf
# rpmconf -a

Keep Default RPM Settings
Keep Default RPM Settings

Next, perform a clean-up of all the packages you don’t require.

# package-cleanup --leaves
# package-cleanup --orphans

Clean RPM Packages
Clean RPM Packages

Step 3: Install the dnf in CentOS 7

Now install the dnf package manager which is the default package manager for CentOS 8.

# yum install dnf

Install dnf in CentOS 7
Install dnf in CentOS 7

You also need to remove the yum package manager using the command.

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

Remove Yum in CentOS 7
Remove Yum in CentOS 7

Step 4: Upgrading CentOS 7 to CentOS 8

We are now ready to upgrade CentOS 7 to CentOS 8, but before we do so, upgrade the system using the newly install dnf package manager.

# dnf upgrade

Upgrade CentOS 7
Upgrade CentOS 7

Next, install CentOS 8 release package using dnf as shown below. This will take a while.

# dnf install http://vault.centos.org/8.5.2111/BaseOS/x86_64/os/Packages/{centos-linux-repos-8-3.el8.noarch.rpm,centos-linux-release-8.5-1.2111.el8.noarch.rpm,centos-gpg-keys-8-3.el8.noarch.rpm}

Note: CentOS 8 is dead and all the repos have been moved to vault.centos.org.

Install CentOS 8 Release Packages
Install CentOS 8 Release Packages

Next, upgrade the EPEL repository.

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

Upgrade EPEL Repository
Upgrade EPEL Repository

After successfully upgrading the EPEL repository, remove all the temporary files.

# dnf clean all

Remove the old kernel core for CentOS 7.

# rpm -e `rpm -q kernel`

Remove Old CentOS 7 Kernel
Remove Old CentOS 7 Kernel

Next, be sure to remove conflicting packages.

# rpm -e --nodeps sysvinit-tools

Thereafter, launch the CentOS 8 system upgrade as shown.

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

CentOS 8 System Upgrade
CentOS 8 System Upgrade

Note: If you get errors about conflicting packages, for example in my case there were conflicts about the existing python36-rpmconf package. I removed this package, similarly if you get any conflicts just remove those packages and try running the above upgrade command.

Step 5: Install the New Kernel Core for CentOS 8

To install a new kernel for CentOS 8, run the command.

# dnf -y install kernel-core

Install Kernel in CentOS 8
Install Kernel in CentOS 8

Finally, install CentOS 8 minimal package.

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

Now you can check the version of CentOS installed by running.

# cat /etc/redhat-release

Check CentOS Version
Check CentOS Version

If you see the above output, I have successfully upgraded from CentOS 7 to CentOS 8.5 release.


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