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Custom Debian Distributions
Chapter 2 - What are Custom Debian Distributions?


2.1 What is Debian?

The core of an operating system is a piece of software which interacts with the hardware of the computer and provides basic functionality for several applications. On Linux based systems the so called kernel provides this functionality and the term Linux just means this core without those applications which provide the functionality for users. Other examples are the Hurd or the flavours of the BSD kernel.

Many applications around UNIX like kernels are provided by the GNU system. That is why Linux based operating systems are pronounced GNU/Linux system. The GNU tools around the Linux kernel build a complete operating system.

Users do not need only an operating system. They also need certain applications like web servers or office suites. A distribution is a collection of software packages around the GNU/Linux operating system which satisfy the needs of the target user group. There are general distributions which try to support all users and there are several specialised distributions that are targeting on a special group of users.

Distributors are those companies that are building these collections of software around GNU/Linux. GNU/Linux is Free Software and the user who buys a distribution pays for the service which the distributor is providing. These services are:

Most distributors ship their distribution in binary packages. Two package formats are widely used:

RPM (RedHat Package Manager)
which is supported by RedHat, SuSE, Mandrake and others.
DEB (Debian Package)
used by Debian and derived distributions.

All GNU/Linux distributions have a certain amount of common ground, and the Linux Standard Base (LSB) is attempting to develop and promote a set of standards that will increase compatibility among Linux distributions and enable software applications to run on any compliant system.

The very essence of any distribution, (RPM, DEB, Source, tarballs or ports) is the choice of policy statements made (or not made as the case may be) by the creators of the distribution.

Policy statements in this sense are things like "configuration files live in /etc/$package/$package.conf, logfiles go to /var/log/$package/$package.log and the documentation files live in /usr/share/doc/$package."

Following the policy statements are the tool-chains and libraries used to build the software, and the lists of dependancies which dictate the pre-requisites and order in which the software has to be built/installed. (It's easier to ride a bicycle if you put the wheels on first. ;-) )

It is this adherance to policy which causes a distribution to remain consistant within its own bounds. At the same time, this is the reason why Packages can not always be safely installed across Distribution boundaries. A 'SuSE' package.rpm might not play well with a RedHat package.rpm, although the packages work perfectly well within their own distributions. A similar compatability problem could also apply to packages from the same distributor, but from a different Version or generation of the distribution.

As you will see later in more detail, Custom Debian Distributions are just a modified ruleset for producing a modified (specialised) version of Debian GNU/Linux.

A package management system is a very strong tool to manage software packages on your computer. A large amount of the work of a distributor is building these software packages.

Distributors you might know are Mandrake, RedHat, SuSE (Novell) and others.

Debian is just one of them.

Well, at least this is what people who do not know Debian right might think about it. But in fact Debian is a different kind of distribution ...


2.2 What is Debian? (next try)

The Debian Project is an association of individuals who have made common cause to create a free operating system. This operating system that we have created is called Debian GNU/Linux, or simply Debian for short.

Moreover, work is in progress to provide Debian of kernels other than Linux, primarily for the Hurd. Other possible kernels are the flavours of BSD and there are even people who think about ports to MS Windows.

All members of the Debian project - who are called Maintainers - are connected in a Web of trust which is weaved by signing of GPG keys. One requirement to become a member of the Debian project is to have a GPG key signed by a Debian developer. Every time one Debian developer meets an other developer they sign their keys and in this way the web of trust is weaved.


2.3 Differences from other distributions


2.4 Custom Debian Distributions

Debian contains nearly 10000 binary packages and this number is constantly increasing. There is no single user who needs all these packages (even if conflicting packages are ignored).

The normal user is interested in a subset of these packages. But how to find out which packages are really interesting for the actual user?

One solution is provided by the tasksel package. It provides a reasonable selection of quite general tasks which should be solved with the computer which is intended to run Debian GNU/Linux. But this is not really fine grained and does not fit the needs of user groups with special interests.

Custom Debian Distributions (formerly known as Debian Internal Projects) try to provide a solution for special groups of target users with different skills and interests. Not only handy collections of specific program packages but care for easy installation and configuration for the intended purpose.

To clarify a common misunderstanding: Custom Debian Distributions are no fork from Debian. They are completely included and if you obtain the complete Debian GNU/Linux distribution you have all available Custom Debian Distributions included.


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Custom Debian Distributions

9 April 2004

Andreas Tille tille@debian.org