What do I change /etc/apt/sources.list to, and how do I fix unable-to-install?

Summary:
========

1. I have a Live Knoppix DVD installed to my hard drive (DVD release
KNOPPIX_V7.0.2DVD-2012-05-30-EN), and have been using it in this form for about
two and a half years.

But I seem to have met a serious problem. At the moment, get-apt and Synaptic
won't let me install packages (80% of the time), because of things like unmet
dependencies. My thread at

http://www.linuxquestions.org/questi...71#post5597871

explains the problem in full.

2. The above thread indicates that my can't-install problem has probably been
caused by having MIXED REPOSITORY TYPES in /etc/apt/sources.list.

I believe this means mixing unstable, testing, and stable, and mixing such as
squeeze and wheezy.

I've shown my sources.list at 2. under "Full Details".

I don't think I've changed sources.list since I installed the Live Knoppix
DVD to my hard drive. So I've been doing installations since the very beginning,
with this sources.list, UNAWARE THAT IT'S MIXED REPOSITORY TYPES COULD CAUSE ME
TROUBLE.

Since installing the DVD to the hard drive, I've installed about 30 packages by
myself (mainly using Synaptic).

3. Main Question 1:

I get very confused about what the entries in sources.list mean, so could you
confirm if there ARE mixed repository types in there please.

If so, could you tell me what entries I should have in there, and what to
remove?

Presumably I need to specify a repository whose packages will minimise conflicts
with the existing packages on my system.

The Debian version on my hard drive is "wheezy/sid" according to "3." under
"Full Details".

Main Question 2:

Could you tell me how to fix the present problem of not being able to install
packages please? I believe that correcting sources.list alone won't fix this.

I've described what another user suggests as a way to fix the can't-install
problem, at "5." under "Full Details", but I'd be most grateful if you could
tell me if you think this will work.


Full Details:
=============

1. What the release is of my Live Knopix DVD.
=============================================

My system is a Live Knoppix DVD that I installed on my hard drive using 0wn,
in about Jan14.

To check what the particular release is of the DVD, I put it in the DVD drive,
and viewed it in file manager. I believe the following filename shows what the
release is:

/media/sr0/KNOPPIX_V7.0.2DVD-2012-05-30-EN.iso

I had the DVD for a while before installing it, in case you're wondering why I
installed that release.

2. The contents of my /etc/apt/sources.list is as follows:
================================================== ========

# Debian/Squeeze is the stable base for this installation
deb http://ftp.de.debian.org/debian stable main contrib non-free
deb http://security.debian.org stable/updates main contrib non-free

# testing/unstable/experimental contain newer versions, but
# packages from there are not being installed by default, unless
# they came from there in the first place.
deb http://ftp.de.debian.org/debian testing main contrib non-free
deb http://security.debian.org testing/updates main contrib non-free
deb http://ftp.de.debian.org/debian unstable main contrib non-free
deb http://ftp.de.debian.org/debian experimental main contrib non-free

# Debian/volatile contains quickly changing data like spam- and virusfilter
databases
# Does not exist anymore
# deb http://volatile.debian.org/debian-volatile stable/volatile main contrib
non-free
deb http://ftp.de.debian.org/debian stable-updates main contrib non-free

# Knoppix repository
deb http://debian-knoppix.alioth.debian.org ./

# x2go
# deb http://x2go.obviously-nice.de/deb/ lenny main
deb http://packages.x2go.org/debian squeeze main
deb http://packages.x2go.org/debian wheezy main
deb http://packages.x2go.org/debian sid main

3. What my system believes my distribution and version is.
================================================== ========

I ran the following 3 commands, to see what my system believes is the
distribution and version on my hard drive:

i) $ cat /etc/issue
Debian GNU/Linux wheezy/sid \n \l

ii) $ cat /etc/debian_version
wheezy/sid

iii) $ cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux wheezy/sid"
NAME="Debian GNU/Linux"
ID=debian
ANSI_COLOR="1;31"

So my system believes that my distribution is Debian and version "wheezy/sid".
Is this actually correct, or is this a nominal interpretation?

4. Should I specify one SPECIFIC thing like "stable" or "wheezy" in sources.list?
================================================== =================

If my system is actually Debian "wheezy/sid", am I right in thinking that
"wheezy/sid" means

the UNSTABLE distribution of "wheezy" (Debian version 7)?

If so, does this mean that in order to make sure I don't mix repository types in
sources.list, that all the entries in there need to be "unstable wheezy"?

But I understand that it's normally not a good idea to get packages from an
UNSTABLE repository. Therefore is it more sensible to use a stable wheezy
repository?

Or should I be using the stable Squeeze (Debian version 6 I believe) repository?

5. Are the following suggestions good ones for fixing my can't-install problem?
================================================== =============================

The following are 2 suggestions I found about how to fix the problem of not
being able to install packages, once sources.list has been corrected.

Could you tell me if you think the suggestions are good ones, or whether you
have a better one. Please would you note my question after Suggestion 2.

The suggesions are at

http://unix.stackexchange.com/questi...kages-with-apt

Suggestion 1:

apt-get update
apt-get -f install

Suggestion 2

(Note: the following solution relates to the poser's particular setup, so the "sed" line may not apply to me):

Squeeze has been deprecated, You have to do :

sed -i 's/squeeze/wheezy/g' /etc/apt/sources.list
apt-get update
apt-get -f dist-upgrade

MY QUESTION:

I notice that Suggestion 2 refers to "apt-get -f dist-upgrade". "man apt-get"
doesn't document the use of -f with dist-upgrade. If I use this combination,
will it correct the package conflicts that I appear to have, but NOT do an
upgrade (I DON'T want to do an upgrade)?