I'd like to get the latest 64-bit dev build of QGIS on my Ubuntu setup.
How exactly do I go about it?
I assume it's some kind of arcane terminal command.
you need to add the ppa of ubuntugis first.
From commandline:
sudo add-apt-repository ppa:ubuntugis/ubuntugis-unstable
sudo apt-get update
the add the following line to the file /etc/apt/sources.list (you can also use the sofware center for that)
deb http://qgis.org/debian-nightly precise main
then install qgis
sudo apt-get update
sudo apt-get install qgis