RE: blatent self promotion: apt/dpkg beginner guide

["Sean 'Shaleh' Perry" <shaleh@valinux.com>]

/var/lib/dpkg/info
  location of the package maintainer scripts (postinst, prerm, etc) as well as
  other pieces of packaging data like md5sums, conffile lists, etc.

auto-apt
  useful tool, play with it and document it here

your data on dpkg --set-selections is wrong:
sudo dpkg --set-selections hold foo
dpkg: --set-selections does not take any argument

proper call is:
dpkg --set-selections<enter>
foo hold<enter>
Ctrl-D

or maybe echo "foo hold" | dpkg --set-selections.