Ubuntu install a proposed update (pre-release)
Either you want to help testing new Ubuntu releases or you want to have an update that has not been released yet. This is not unlikely as a release of an update could take long and sometimes forever.
Installing and testing proposed (pre-release) updates:
Start program 'Software & Updates':
software-properties-gtk
Select the tab 'Updates' and then check 'Pre-released updates' archive. Note: afterwards you can turn this off again.
You can configure apt to allow selective installs of packages from it instead of upgrading all of your packages to the -proposed versions. You will need to know your Ubuntu release and codename:
lsb_release -rc
Now create the following file an contents. Note: use the proper release codename (14.04=trusty, 12.04=precise, etc.)
sudo gedit /etc/apt/preferences
Package: * Pin: release a=trusty-proposed Pin-Priority: 400
Test this by simulating an upgrade with apt:
sudo apt-get upgrade -s
Manually install update:
sudo apt-get install nautilus/trusty-proposed
Again to check if it worked:
sudo apt-get install nautilus/trusty-proposed
TODO: rolling back the update