Versioning and Releases

CentOS version numbers for releases older than 7.0 have two parts, a major version and a minor version, which correspond to the major version and update set of Red Hat Enterprise Linux (RHEL) used to build a particular CentOS release. For example, CentOS 6.5 is built from the source packages of RHEL 6 update 5 (also known as RHEL version 6.5), which is a so-called "point release" of RHEL 6.

Starting with version 7.0, CentOS version numbers also include a third part that indicates the monthstamp of the source code the release is based on. For example, version number 7.0-1406 still maps this CentOS release to the zeroth update set of RHEL 7, while "1406" indicates that the source code this release is based on dates from June 2014. Using the monthstamp allows installation images to be reissued for (as of July 2014) oncoming container and cloud releases, while maintaining a connection to the related base release version.

Since mid-2006 and starting with RHEL version 4.4, which is formally known as Red Hat Enterprise Linux 4.0 update 4, Red Hat has adopted a version-naming convention identical to that used by CentOS (for example, RHEL 4.5 or RHEL 6.5).

To check your version, from a terminal window, use the following command:

  cat /etc/centos-release

Or, you can use this command:

  cat /etc/redhat-release
  echo "I am running: `cat /etc/redhat-release` (`arch`)"

Here is an example of the output:

  CentOS Linux release 7.2.1511 (Core)

Kernel Version

You may also want to check what kernel is running on your CentOS server. You can check which kernel you are using by running:

uname -a

Here is an example of the output:

  Linux hdcentos 3.10.0-327.10.1.el7.x86_64 #1 SMP Tue Feb 16 17:03:50 UTC 2016 x8
  6_64 x86_64 x86_64 GNU/Linux

You may notice that this is not the latest kernel, but this it typical. The most important thing is that you are running the latest kernel for your CentOS server.

This is the kernel that is actually running on your server. There you could be newer kernels installed on your CentOS server but not actually running. You can list the installed kernels using yum or rpm. You can then see which kernel will start on boot by checking your /etc/grub.conf.

If you run a CentOS server, keeping track of CentOS versions is important. The best way to do this is to follow the CentOS web site so you can stay on top of your chosen Linux distribution.