pbuilder-uml uses a User-mode-linux system, and builds Debian packages inside the UML image. It is an ideal system to use to check that a package has correct build-dependencies. It uses apt extensively, and a local mirror, or a fast connection to a Debian mirror is ideal, but not necessary. . Requires user-mode-linux to function correctly . "pbuilder-user-mode-linux create" uses rootstrap to create UML image . "pbuilder-user-mode-linux update" updates the image to the current state of testing/unstable/whatever . "pbuilder-user-mode-linux build" takes a *.dsc file and builds a binary in the UML