# apt-get install mdbtools
Leyendo lista de paquetes... Hecho
E: Registro inválido en el archivo de preferencias, no hay cabecera de paquete
#vi /etc/apt/preferences
Package: *
Pin: release a=stable
Pin-Priority:700
Package: *
Pin: release a=testing
Pin-Priority:650
#Package: *
#Pin: release a=unstable
#Pin-Priority:600
# vi /etc/apt/apt.conf
PT::Cache-Limit ":8388608";
APT::Default-Release "stable";
#vi /etc/apt/sources.list
#deb file:///cdrom/ sarge main
#Stable
deb
http://http.us.debian.org/debian stable main contrib non-free
#deb
http://non-us.debian.org/debian-non-US stable/non-US main contrib non-free
deb
http://security.debian.org stable/updates main contrib non-free
deb
http://www.debian-multimedia.org stable main
#deb-src
http://http.us.debian.org/debian stable main contrib non-free
#deb-src
http://non-us.debian.org/debian-non-US stable/non-US main contrib non-free
#deb
http://security.debian.org/ sarge/updates main
#Testing
deb
http://http.us.debian.org/debian testing main non-free contrib
#deb
http://non-us.debian.org/debian-non-US testing/non-US main contrib non-free
deb
http://security.debian.org testing/updates main contrib non-free
#Unstable
#deb
http://http.us.debian.org/debian unstable main non-free contrib
#deb
http://non-us.debian.org/debian-non-US unstable/non-US main contrib non-free
#deb
http://security.debian.org unstable/updates main contrib non-free