How do I find add-ons for packages when using the command line?

My question is a little bit different from others already asked, I guess. I've already searched for answers, but I didn't find anything related.

For example, I've always installed K3B via Terminal with the following command "sudo apt-get install k3b". It always worked, of course. One day, I decided to install it via Ubuntu Sofware Center and, to my surprise, there were a few Add-ons I didn't know about. I checked some of them to be installed as well because I found them useful.

Now, here's my question: When we try to install a software via Terminal and this software has add-ons, how do we know that? And how do we install the add-ons via Terminal?

I suppose we have to know the names of the add-ons first, and then install them one by one, once the main software has already been installed. But how do we get to know those names via Terminal? Using the Software Center is cool because it shows the add-ons, a brief description for each one and their names in brackets, right? How about that via Terminal?

I had never paid attention to this until I used the Software Center. By the way, K3B was just an example, of course.

Those addons are suggested packages which are meant to enhance your experience with k3b. But those are not essentials for k3b to work properly.

In terminal, you can know the add-on names (at least some of those) by using apt-cache depends k3b command. The add-on names will be shown under "Suggest:" section. For example:

apt-cache depends k3b | grep Suggests
k3b
  Suggests: k3b-extrathemes
  Suggests: normalize-audio
  Suggests: sox
  Suggests: movixmaker-2
  Suggests: libk3b6-extracodecs
  Suggests: vcdimager

Please note that, suggested packages are not essentials. Also note, apt-get will install packages which are essential to run k3b (called dependency) and those packages which are recommended.

You may want to visit these link to get some info about this topic:

• Recommended and Suggested packages, Debian Faq
• Debian policy, Debian Handbook

Also check this question on Superuser.com

• What is the difference between recommended and suggested packages

As a summary:

• A depends packages in one, which is required to run the software
• A recommended package in one, which is required for the software to be functional.
• A suggested package in one, which can enhance the usability of the software.

Note, Ubuntu install first two category of the software by default from both Software Center and from terminal. So, you are not loosing anything essential. But still you can install them. Also note, Software Center does not install them automatically.

To install suggested packages also from terminal

If you want to install suggested packages from terminal, you can use this command

 sudo apt-get --install-suggests install k3b

This command will install all the suggested packages as well as dependency and recommended packages.

To permanently configure apt to install suggested packages

If you want to configure apt-get permanently to automatically install suggested packages also, You can do this:

1. Create a file in /etc/apt/apt.conf.d with name 99mysettings

    gksu gedit /etc/apt/apt.conf.d/99mysettings
   

2. Then add the configuration option in that file

    APT::Install-Suggests "true";     
   

3. Then save the file and exit gedit.

From now, the suggested packages will also get installed automatically by apt-get.

Please note that, apt-get will only install those packages if it finds them in any repositories, Otherwise, it simply ignores them and proceed with installation.

When you install a program through the terminal it will also tell you suggested packages (add-ons, etc). i.e.:

sudo apt-get install k3b
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Suggested packages:
  k3b-extrathemes sox movixmaker-2 libk3b6-extracodecs vcdimager
The following NEW packages will be installed:
  k3b
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.

You should be able to use sudo apt-cache search <name> This should return all packages that have are related to in any way possible.