how to view all the uninstalled packages in a debian based linux?

dpkg - > is a debian package manager command
dpkg -l - > will list all the packages with their status installed/deinstalled/removed/half-installed etc

The first 2(actually 3) letters of the output of " dpkg -l " command are significant to us, because it tells the current state of the package.  if it is
ii  - installed
rc - removed but configuration files are kept
So, " $dpkg -l | grep ^rc "
will display all the package that are removed but configuration files are still kept.

Note: if you purged configuration files of a package during removal using
"apt-get remove --purge < package_name >" then those packages will not be displayed.

For more information about dpkg :
i) man dpkg
ii) dpkg -l - > Read the first 4 lines ;-)
iii) Read this http://linuxprograms.wordpress.com/2010/05/11/status-dpkg-list/

How to install/configure skype in debian based linux?

skype:

 is a VoIP based software application which is mainly used for peer to peer phone/video call, instant messaging over internet connection in free of cost^*.  To use this one should have a valid user account with skype.  Now, skype have features like file transfer,  video conferencing also.

free of cost^*  - Only between skype accounts,  yes you can call/sms any landline/mobile phone... but with applicable call charges :(.

1. Download the latest linux version of skype from here.  Select your exact distribution like debian, Opensuse, ubuntu etc..

2. Install the downloaded package using your package manager.  I am using BOSS GNU/Linux 4.0 and it is a debian based one.  So, the following steps regarding installation is applicable to only to the debian based linux  distributions like ubuntu, BOSS GNU/Linux, linuxmint, knoppix etc.

GUI way:
Right click the downloaded skype-xy-z.deb package -> Open with gdebi package installer -> Install

Command line way:
$dpkg -i fullpath-to-downloaded-directory/skype-xy-z.deb

Once installed, as per your distribution's application classification skype menu will be placed either below internet or sound & video.  In BOSS GNU/Linux it will be placed under Internet.

3. If you have skype user account already then just use it.  If not create your user account by "Do not have user account.? create " link from the Skype GUI application.

GUI -> Graphical User Interface
BOSS -> Bharat Operating system solutions
GNU -> GNU's Not Unix
VoIP - Voice over IP(Internet Protocal)

When a new package installed.., What are the files installed & where they are?

In Debian linux(which uses apt-get & dpkg for package mangement) we can find out what are the files
get installed when a new package installed into your system. There are two ways to do this.

GUI Way:
System -> Administration -> Synaptic Package Manager
1. Now you got a GUI window. In that window on left side select "status" button & then "Installed"
2. Now you will see all the installed packages in your system on the right side.
3. Select the package to which you want to get the information, then right click select "properties"
4. Now you will get a new window with tabs "common, dependencies, installed files.. etc". Click the installed files tab.

Now you can see all the files installed in your system regarding that particular package with the full path to those files. :)

CUI Way(Terminal):
Issue the following command in terminal
#dpkg -L "packagename" | more
Note: Replace with the package which you want without quotes. I am using the debian derived Indian linux distro "BOSS- Bharat Operating System Solutions"



This will be useful when you are not sure/know where the configuration, log files, command regarding particular package is.

how to get the information/details about the installed packages in debian linux?

$dpkg -s "package-name"

-s <- is the option for find out the status of the given gives information like

1. The package is installed or not, removed
2. size of the installed package
3. Architecture support
4. Dependency
5 Version and so..

How to find out the package from which a command (comes) is available?

From starting of the linux usage we all using the command mkdir, copy, mv .. etc.
So do ever wish to identify from which package a certain command is (installed) availabe.

If you got a doubt like so, here is the solution how to find the package name that provide the certain command.

1. First find out the place where the command(binary) is? using

$whereis
Ex:$whereis mv
$mv: /bin/mv /usr/share/man/man1/mv.1.gz <--Out put for above command is like this

So, the command binary of the command is resides in the folder /bin/

2. Now issue the following command to find out the package which provides 'mv' command
$dpkg -S
EX:$dpkg -S /bin/mv
$coreutils: /bin/mv <-- Output for above command is like this

So, the package(name) that provides mv is "coreutils".

Thats it.. :)