Hello Linux Geeksters. As you may know, all the Ubuntu systems come with a bunch of 15 to 20 wallpapers, submitted and voted by the community to be used as defaults.
Starting with Ubuntu 9.10 Karmic Koala, the wallpapers used on each Ubuntu system have been packed in .deb packages, so that they can be easily available for other systems.
In this article I will show you how to easily get all the default wallpapers of Ubuntu 9.10 (Karmic), Ubuntu 10.04 (Lucid), Ubuntu 10.10 (Maverick), Ubuntu 11.04 (Natty), Ubuntu 11.10 (Oneiric), Ubuntu 12.04 (Precise), Ubuntu 12.10 (Quantal), Ubuntu 13.04 (Raring) and Ubuntu 13.10 (Saucy) on your Ubuntu 14.04 Trusty Tahr system or derivative: Linux Mint 17 Qiana, Pinguy OS 14.04, Elementary OS 0.3 Isis, LXLE 14.04, etc.
The below command downloads all the wallpapers, from Ubuntu 9.10 to Ubuntu 13.10 in /usr/share/backgrounds/, these wallpepers being available under System Settings > Appearance.
$ sudo apt-get install ubuntu-wallpapers-karmic ubuntu-wallpapers-lucid ubuntu-wallpapers-maverick ubuntu-wallpapers-natty ubuntu-wallpapers-oneiric ubuntu-wallpapers-precise ubuntu-wallpapers-quantal ubuntu-wallpapers-raring ubuntu-wallpapers-saucy
Also, if you are using an Ubuntu 14.04 derivative system, but want the Ubuntu 14.04 wallpapers on your system, do:
$ sudo apt-get install ubuntu-wallpapers-trusty