I will show how to create a transparent shell on ubuntu desktop, and first make sure Compiz fusion has been installed

UPDATE: USE THIS ALTERNATIVE WAY IF THIS POST NOT WORK ON HIGHER UBUNTU EDITION!

You will see the following figure if everything below done

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Open a gnome terminal (Applications–>Accessories–>Terminal),then go to Edit–>Profiles

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click New in the next window:

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type profile name,it’s trans in my case :

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click Create ,then set as following :
Show menubar: off
Initial title: trans
Dynamically-set title: Isn’t displayed
Color scheme: Black on white
Transparent Background: on
Set the transparency down to “None”
Scrollbar: disabled

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Close the window when settings done,and do like this if you want

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close the terminal window.

Open CompizConfig setting by click System–>Preferences–>CompizConfig Setting Manager

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go to the Window Decoration,click it on and double click, add !title=^trans$ to the Decoration windows field

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click Back,go to Windows Rules plugin,click it on then  double click and do as following:

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turn to Size rules tab,click New,put the Width and Height as you want for your shell

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at last go to Place windows,click it on go to the Fixed Window Placement tab,click new

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put x and y coordinates of the default position you want for your shell.

Now open a terminal window, (code:gnome-terminal –window-with-profile=trans if you do not set Profile used when launching a new terminal:trans) and you will see the figure at the beginning

Tips:

you can make it run at login by type gnome-terminal –window-with-profile=trans in command field