Hi ,
testing, 2.6 .

1. Looking at the varies source lists (at the "post source list" thread) I see testing ,unstable and stable at the same source list, what's the logic of that and how does the apt behave ?

2. Do you think I should add sources to the one I got at the (testing) installation ?

Thanks.

1. You can actually configure your system to use more than one distribution and then you can ask Debian to prefer only a particular distribution during upgrades while having the ability to install from other distributions if you need to.

Eg. You can set the preferred distribution to "testing" while having "unstable" to install apps not present in "testing" as yet.

2. You don't have to unless you really need packages from "unstable". Otherwise you can also use www.apt-get.org to configure unofficial package repositories to install apps which are not present in the official distro.

1. Debian's packages have three versions: stable, testing, unstable.
The packages in stable are nearly no bugs, but too old. They are fit for server. The testings' are tested by the offical oganization, and the packages are newer, so they are fit for desktop. The unstables' are only tested by developer and are newest, but has too bugs. They are fit for the developers which develop based on linux.

2. If you add stable, testing and unstable sources into your 'sources.list', the package you get is actually unstable. So I think it's needless to add all sources to the 'sources.list'. But you could use different sites' sources. That means you could use 'us.debian.org' and 'ftp.se.debian.org' the same time.

It is fuzzy logic

If you have nothing to do for the next hour, have a look at

Thanks I understand now, still if I add source list ,specific to a certain package (for example " deb ftp://ftp.nerim.net/debian-marillat/ unstable main" for mplayer)this will add just the mplayer as unstable package ?

Almost, but not quite. The repository at debian-marillat is not just specific to one package. It doesn't have all the main repository pacakges, but it has more than just mplayer. If you add the line
deb ftp://ftp.nerim.net/debian-marillat/ unstable main
to your sources.list, and then run (as root or with sudo)
apt-get update
then your system will add the unstable packages available at debian-marillat to your packages index. That means that if you apt-get a package (say mplayer) and APT finds a newer version of it there, it will indeed get the unstable version from debian-marillat. Unfortunately, it will also prefer the unstable version of any dependencies since they are newer, and this can quickly lead to a cascading effect and you'll end up with a whole lot of unstable pacakges in your testing, which can definitely be against your intention.

Using a mixed system can be pretty delicate. To avoid problems, you can use apt-pinning that Harishankar referred to. Here is a great place to start:
http://wiki.serios.net/wiki/Apt-Pinning_on_Debian

If you just want mplayer, it's available from the testing repository of debian-marillat. You can just add the following line to sources.list:
deb ftp://ftp.nerim.net/debian-marillat/ etch main

If you really specifically need the package versions from unstable, then I would definitely prefer the apt-pinning method as opposed to just adding unstable repositories to the list without telling APT your preferences.

Thanks,
I really like the quick and detailed answers I get in this forum , very helpful for a newbie like myself.

Yeah, simple problems sometimes get quick answers. The stuff you really need help with can go longer though!

Once you're done with the hard work, check out this article:
http://www.debian-administration.org/articles/201

By the way, it's good to write out such detailed answers, because it saves time later when people are searching the forum for answers. I have to say though that a quick Google search would have turned up your solution pretty quickly.

Unstable isn't for developers. Unstable is perfectly fit for desktops if you have some experience. Developers 'dump' their stuff in experimental and that's where you can expect to find buggy stuff.