Minor upgrades and version numbers on CentOS

Question

I installed CentOS 6.0. Later I ran yum update to apply software updates. After that my operating system version changed to 6.3. Why did the version change? How far up will it go? How can I choose whether to keep running 6.0 or apply minor upgrades, and why should I change one or the other?

Answer 1

yum update also update centos-release rpm which contains /etc/centos-release. Here is the CentOS release scheme.

Answer 2

Why did the version change?

If you look in /etc/yum.repos.d/CentOS-Base.repo, you'll see the baseurl or mirrorlist is configured to look at what $releasever is set to. $releasever is set to 6 and if you look at how a CentOS mirror is configured, the 6 directory is just a symlink to the whatever the latest is, which is 6.3 ATM. If you look at a directory for an older release like 6.0, you'll see it is empty and has a readme telling you you should be using 6 but if you need 6.0 it is in the CentOS vault

How far up will it go?

There's no telling but it will always be 6.x. Minor version bumps come about every 6 months, for the first few years, then less frequently after that, maybe once a year, so it will probably get up in the teens. Look at CentOS 5, which is on 5.9 now and still has 4 years of support on it for an example.

If you're not familiar with the RHEL life cycle and are concerned with an updating breaking something, you may want to read about it.

How can I choose whether to keep running 6.0 or apply minor upgrades, and why should I change one or the other?

In general, you want to be running the latest in the 6.x line, the 6.0 version is no longer supported and you will not get any more updates for it. You should read up on the RHEL release cycle and how the updates work before you decide to stick with 6.0.

If you have some unusual circumstance and need to stay on 6.0, you'd have to manually configure the /etc/yum.repos.d/CentOS-*.repo files and disable the mirrorlist (since the mirrors don't carry 6.0) and configure your baseurl to look at http://vault.centos.org/6.0/updates/$basearch/ replacing updates with the appropriate directory name for each of the repos.

Answer 3

There are two parts of this version number. The first one, 6, is the major release version for this Linux distribution. The second one, 0 or 3, represents the update number for this release. The update is something like a minor release, or a service pack. If two version only differs in the second number, then they really have a few difference.