$ dpkg -S /etc/apt
debconf, unattended-upgrades, aptdaemon, apt, update-notifier-common, aptitude: /etc/apt
gago@Ubuntu-11-10:~$ dpkg -S /etc/apt
aptitude, aptdaemon, update-notifier-common, apt, unattended-upgrades, debconf: /etc/apt
gago@Ubuntu-11-10:~$ dpkg -S /etc/apt debconf, unattended-upgrades, aptdaemon, apt, update-notifier-common, aptitude: /etc/apt
aptitude, aptdaemon, update-notifier-common, apt, unattended-upgrades, debconf: /etc/apt
dpkg-query: no path found matching pattern *debconf,*.
dpkg-query: no path found matching pattern *unattended-upgrades,*.
dpkg-query: no path found matching pattern *aptdaemon,*.
dpkg-query: no path found matching pattern *apt,*.
dpkg-query: no path found matching pattern *update-notifier-common,*.
dpkg-query: no path found matching pattern *aptitude:*.
aptitude, aptdaemon, update-notifier-common, apt, unattended-upgrades, debconf: /etc/apt