What is the relationship between Unity, Gnome, Gnome 3, Compiz, Metacity, and LightDM?

Question

I am using ng-repeat functionality of angular js

<th ng-repeat="x in data.items[0].bf_val " >
		<div style="width: 70px" > BF Score</div>
	  </th>

Now instead of just BF Score . For every row I want a number before it . Like first row should read (1st BF Score) , second row as (2nd BF Score) and so on . can this be done ?

Solution

You only need to know 4 terms:

• Display manager
• Window Manager
• Graphical User Interfaces (GUI)
• Desktop Environments

Display manager

Examples are LightDM, GDM, KDM, and LXDM. They normally have display manager somewhere in their names. These start the X server at boot and provide a login screen. They often let you select a window manager and/or desktop environment as part of logging in.

Window Manager

Compiz, Metacity, Mutter, W9dk, fluxbox are window managers. There are too many to list. If you want you can check all the packages that provide x-window-manager to get an incomplete list of the window managers in Ubuntu. These only are responsible of drawing the application borders, managing the position of the windows, themes and decorations.

Grapical User Interfaces (GUI)

Anything that the user interacts with in any graphical way, with icons and representations. Window Managers, Display Manager and Graphical shells, applications, etc. falls in this category. Whatever the user is using that is represented predominantly in a graphical way is a GUI.

Desktop Environments

In the Linux world, it's referred to as a set of applications, packages, services, etc. that provides a complete and balanced ecosystem for the user. Unlike Window Manager or Desktop Manager, Desktop Environments take care of everything. From the login screen through your mail application, the network manager, text editor, the system settings, image viewer, file manager, etc. There are 4 well known Desktop Environments in Linux and Ubuntu:

• GNOME
• KDE Desktop Environment
• LXDE: Lightweight X11 Desktop Environment
• XFCE Desktop Environment

These all have a complete set of applications, settings, services, desktop/file/window managers, internet browser, etc.

---

So, to address your specifics concerns:

LightDM appears as a service on my installation and is a 'Window Manager'

False, LightDM is a Display Manager.

how is this related to Compiz, which is also a Window Manager but not a service?

Have nothing in common. Both have different functions. Compiz is a window composer, window decorator, a window manager.

Is Metacity also a Window Manager?

Yes.

Then there comes Gnome 3, Unity, Gnome Shell and Gnome - all of which seem to be different things.

Gnome 3, Gnome Shell and Gnome are terms used colloquially as the same thing. Unity is totally different. Unity is another shell opposed to Gnome/3/Shell. Gnome 3 Shell has been commonly called as Gnome Shell in the past, right now saying GNOME, GNOME 3 Desktop Environment or Gnome Shell carry the same meaning.

Comments

[jII]

Thanks! When I browse through the gconf database, however, I find an entry for /desktop/gnome. However, as far as I know I am using Unity on Ubuntu 12.04. Why then, does gnome exist in the database?

[Braiam]

@jesterII Unity is a shell which use Compiz/Gnome.

[jII]

Then how come comparisons between Unity and GNOME 3 Shell make sense, if Unity is a shell that uses Gnome?

[Braiam]

@jesterII seem like you have many doubts. I suggest you asking a separated question for each of those doubts.

[jII]

I am not doubting your answer, I am asking follow-up questions to help resolve my confusion.

[Steelsouls]

@jesterII I strongly suggest looking at the Wikipedia page for Unity (user interface). I believe it will answer your remaining questions about Unity/Gnome.

[zuba]

Unity is another shell opposed ... Ok, and what is a shell and how it relates to Window Manager, Display Manager, and Desktop Environment ?

[Braiam]

@zuba unix.stackexchange.com/a/149294/41104