Why userland , basesystem and Kernel are together?!

[Cordula's Web]

> > There are several operating systems, Debian, RedHat,
> > Mandrake, which only have in common to use the Linux kernel. 
> 
> This is incorrect. All relevant Linux distributions are not only based
> on the same kernel, but almost almost all of the same userland software
> as well. (Specifically, GNU software, much of which is a core part of
> FreeBSD as well.) The main areas where they differ are the configuration
> details (what files are where, how to configure services such as init
> scripts and networking, etc) and package management. There are of course
> other differences, but these two are the biggies.

All Linux distributions use glibc; while BSDs use their own version
of libc.

But these are only technicalities. More important is that the BSDs
use a central CVS repository for the whole OS (minus third party
packages), whereas in the Linux world, the "vendors" maintain
separate (mostly with source, but sometimes binary-only as well)
collections of separately maintained software.

If the developers of Linux' base utilities, glibc, kernel etc...
submitted all their source code to a "Linux CVS" repo, and all
distributions were built on top of that, they would have adopted
an important part (though not everything) of BSDs philosophy
[putting the different licensing schemes aside for a moment].
However, this is unlikely to happen any time soon (if at all),
mostly for political reasons: the FSF, Linus, and a lot of other
developers would have to agree to share a single repository,
and this is particulary difficult to achieve.

Anyway, both development models are quite viable, and it is
amazing to see how both "camps" are making excellent progress.

-- 
Cordula's Web. http://www.cordula.ws/