How to download the iso file of ubuntu in command line?

I need to install the VirtualBox in the company's server by the client, PuTTY. Then install the ubuntu 14.04 in the VirtualBox. Right now I have find the methods of installing the VirtualBox in the server. However, I cannot download the iso file in the way of command line.


wget "http://web address for direct download of the iso"

Example : wget http://releases.ubuntu.com/14.04/ubuntu-14.04-desktop-amd64.iso