Unix: Apt-Get (Advanced Packaging Tool):Info, Problems and solutions

Apt-Get (Advanced Packaging Tool):

The apt-get command is a powerful command-line tool used to work with Ubuntu's Advanced Packaging Tool (APT) performing such functions as installation of new software packages, upgrade of existing software packages, updating of the package list index, and even upgrading the entire Ubuntu system.

Install a Package:

sudo apt-get install

Remove a Package:

sudo apt-get remove

Update the Package Index:

The APT package index is essentially a database of available packages from the repositories defined in the /etc/apt/sources.list file. To update the local package index with the latest changes made in repositories, type the following: 

sudo apt-get update

Upgragde Packages:

sudo apt-get upgrade

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PROBLEM: Unable to install or remove anything, it gives below error:

root@impetusN087:~# apt-get install synaptic

Reading package lists... Done

Building dependency tree       

Reading state information... Done

You might want to run 'apt-get -f install' to correct these:

The following packages have unmet dependencies:

 python-setuptools : Depends: python-pkg-resources (= 0.6.16-1ubuntu0.1) but 0.6.24-1ubuntu1 is to be installed

 synaptic : Depends: libept1.4.12 but it is not going to be installed

            Depends: libvte9 (>= 1:0.24.0) but it is not going to be installed

            Recommends: rarian-compat but it is not going to be installed

E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

I tried to use

apt-get install

apt-get -f install

apt-get update; apt-get upgrade

but, nothing works.

apt-get install gave me a clue that there's something fishy with sources.list file.  So, I scp that file from someone's system.

Then, tried “apt-get install” , then “apt-get upgrade” , still nothing worked.

Then, I used “apt-get purge python-setuptools”.  All this did is, it deleted all the configuration files for that package.  Then, I used “apt-get install packagename” and works.