CentOS

CentOS was a free and open-source Linux distribution that worked well with Red Hat Enterprise Linux. It was made for people who wanted a stable operating system for their computers and servers without paying.

The first version of CentOS came out in May 2004. It was made from an earlier version of Red Hat and kept getting better over the years. By version 8, CentOS could run on many types of computer processors.

In December 2020, the company behind Red Hat stopped working on CentOS and started a new system called CentOS Stream. But some people still wanted CentOS to continue, so new projects like AlmaLinux and Rocky Linux were created to keep CentOS going.

History

CentOS started as a version of CAOS Linux, a computer system made by Gregory Kurtzer in 2002. Over time, CentOS became very popular.

In 2014, Red Hat, a big company, began supporting CentOS. This helped it grow. But in December 2020, the CentOS team said they would stop making the original CentOS. This made many people unhappy. After this, two new projects started: Rocky Linux and AlmaLinux. These were made to keep the spirit of CentOS alive.

Design

CentOS developers used code from Red Hat to create a system that works like Red Hat's. They changed Red Hat's branding and logos because Red Hat does not allow them to share these. CentOS is free to use. Help with technical issues comes from other users through mailing lists, web forums, and chat rooms.

The project works closely with Red Hat but aims to be open and welcoming to everyone. Even though Red Hat employs many of the main CentOS developers, the CentOS Project relies on contributions from users and support from organizations.

Versioning and releases

CentOS releases

CentOS used to have two numbers for releases before version 7.0. These numbers matched Red Hat Enterprise Linux (RHEL). For example, CentOS 6.5 came from RHEL 6 update 5.

Starting with version 7.0, CentOS added a third number. This showed the month the source code was from. For example, version 7.0-1406 linked to RHEL 7, with "1406" meaning the code was from June 2014. This helped when new versions were needed for containers and clouds.

Since mid-2006, Red Hat started using the same naming as CentOS. For example, RHEL 4.5 or RHEL 6.5.

On September 10, 2019, CentOS delayed work on CentOS 8.1 to focus on CentOS 7.7 because more people were using CentOS 7. After CentOS 7.7 came out, work went back to CentOS 8.0.

CentOS officially released version 8.0 on September 24, 2019. CentOS stopped in late 2021, and its last version was 8.5, released on November 16, 2021. Meanwhile, RHEL kept going and reached version 8.10 by September 2024.

End-of-support schedule

CentOS versions 5, 6, and 7 were supported for up to 10 years because they were based on RHEL. Before that, CentOS 4 was supported for seven years.

Older version information

CentOS version 7

Latest version information

CentOS version 8

AltArch releases

AltArch releases are made by the Alternative Architecture Special Interest Group (AltArch SIG). They support types of computers that the main CentOS versions do not.

Add-ons releases

Software Collections (SCL) is a CentOS collection that offers newer versions of programming languages, database servers, and other packages. These do not replace the regular tools in CentOS. Instead, they are installed in a separate place and can be chosen when needed. For example, the regular versions of Perl or MySQL stay the same.

Releases without upstream equivalents

Some CentOS images have special purposes and no matching versions from Red Hat.

LiveCD and LiveDVD images can boot a computer from a CD or DVD and can also be installed on a hard drive. The set of packages cannot be changed during installation.

MinimalCD images have only the needed packages for installation and use the regular CentOS installer without package choices. More packages can be added after installation using yum.

Main article: CentOS repositories

Special interest groups

Special interest groups, or SIGs, are groups in the CentOS community. They help make special versions of CentOS for different needs. These groups can change and improve CentOS in many ways. They might add newer software, change parts to fit certain needs, offer different desktop options, or make CentOS work on systems it didn’t support before.

Architectures

Since version 8, CentOS works well with x86-64, POWER8, and 64-bit ARM computers. Some older types of computers, like those using IA-32, are no longer supported.

As of December 2015, CentOS also offered versions for ARMv7hl and AArch64 types of ARM computers. There were plans to support more types of ARM computers in the future. You can find CentOS versions on Amazon's EC2 cloud as pre-made images called Amazon Machine Images (AMIs).

Repositories

CentOS had three main repositories with software packages that made up the CentOS system:

• base: held packages that formed CentOS updates.
• updates: held packages for security, bug fixes, or improvements.
• addons: provided packages needed to build the main CentOS packages.

The CentOS Project also offered extra repositories with software not in the default base and updates repositories. These included:

• CentOS Extras: held packages adding features to CentOS.
• CentOSPlus: held packages that updated some base CentOS parts.
• CentOS-Testing: tested packages before they moved to CentOSPlus and CentOS Extras.
• CentOS-Fasttrack: held bug fixes and improvements released between updates.
• CR (Continuous Release): made packages available that would appear in the next CentOS update.
• debuginfo: held packages with symbols for finding problems.
• contrib: held packages added by CentOS users.
• Software Collections: offered newer software versions than those in the base distribution, see above for more information.

CentOS Stream

CentOS Stream is a type of operating system that changes often. It follows the development of Red Hat Enterprise Linux (RHEL). It is for people who want to help and work together in the RHEL community.

Before CentOS Stream, older versions of CentOS were based on RHEL. But CentOS Stream is different. It sits between the fast-changing Fedora Linux and the more stable RHEL. CentOS Stream 9 and RHEL 9 started from the same basic code. So CentOS Stream is often closer to RHEL than Fedora is. The first version, CentOS Stream 8, came out on September 24, 2019. It came out at the same time as CentOS 8. When CentOS 8 stopped getting updates, the CentOS Project made it easy to change from CentOS Linux 8 to CentOS Stream 8.