In this article we will discuss Linux and each distributions release schedule with a focus on how you can update to a newer version if needed. There are many Linux distributions out there, but it can be simple to figure the release schedule as a lot of them are based on three main ones.
In this article I will go through some popular Linux distributions and how they update, and what a new Linux release means. However, since there are so many I cannot cover them all and some may be completely different. I will be covering popular distributions such as Debian and Ubuntu, as well as Fedora and CentOS.
Other distributions are often forks of the ones above, for example Jolicloud and Backtrack Linux are based off Ubuntu. Although, the forks can have their own package manager and update schedule. For example, Backtrack 4 is based on Ubuntu 8.10 which is now not supported by the folks at Ubuntu.
There is a new Ubuntu release every 6 months, one in April and one in October. Most releases are supported for 18 months after their release date until they reach their end-of-life. At this point, they stop getting updates from the Ubuntu team. Every 2 years there is an LTS release which addresses the need for a longer lasting distribution. This is very useful for a large company and is supported for 5 years from release date.
A major update can be done from inside the distribution by typing: sudo apt-get dist-upgrade, but it is often better to do a backup and install the new version fresh. A lot of unexpected problems can occur from upgrades.
A lot of forks such as Mint follow the same release schedule, but some don't as I mentioned earlier. A lot of forks will provide their own packages and updates which will be based around the ones for Ubuntu.
Debian does not have a specific release schedule, but generally there is a new major release every 2 years. Ubuntu is actually a fork of Debian, with a more organized release structure, it uses a common package manager known as apt. You will find a lot of similarities between the two. The method of doing a distribution update is the same.
Debian has updates and then "minor" releases every so often, which used to look like: 5.0r2 for release two. It now follows a more generic GNU style update name, such as 5.02. Like Ubuntu, Debian also has "codenames", for example Debian 5 is known as "lenny" and Debian 6 will be known as "squeeze". Debian is primarily for users who know what they are doing in the Linux world, whereas Ubuntu is more newbie friendly.
Fedora and CentOS
Fedora is very similar to Ubuntu in the fact that it issues an update once every 6 months. However, it is based on Red Hat instead of Debian, and it was created when Red Hat decided to discontinue their free Linux distribution.
CentOS is also based on Red Hat, it has inherited the rather confusing release schedule, for example: 3.9 was released after 4.3. This is because of the "major" and "minor" release strategy they have. A major release constitutes a change in the first number, but the old one may still be stable and supported. A minor release is one where the second number is changed.
This is by no means a full list but I have covered most of the methods of updating. The most common method for distribution updates is to release one every 6 months. However, it is always a good idea to check with your distribution's website. It may have a discussion forum with some details in an FAQ or information section if it not on the main page.
You can also check the time gap between the last release and the current one, this could give you some indication of how long it is before a new update comes around. If you have a specific distribution that is not listed here, and can't figure out the release cycle feel free to comment below.