apt-pinning

Apt-Pinning for Beginners
==========================
allow you to run a mostly-Stable system,
but also track the latest and greatest of those packages that you are most keenly interested in.


กำหนดลำดับ ว่าระบบจะติดตั้งโปรแกรมจาก repo ไหน
===============================
vi /etc/apt/preferences

Package: *
Pin: release n=squeeze-backports
Pin-Priority: 1001

Package: *
Pin: release n=squeeze-updates
Pin-Priority: 950

Package: *
Pin: release n=squeeze
Pin-Priority: 900

Package: *
Pin: release n=stable
Pin-Priority: 800

Package: *
Pin: release a=testing
Pin-Priority: 700

apt-cache policy {package-name}
apt-get -t testing install --no-install-recommends xorg xfce4

more info at http://jaqque.sbih.org/kplug/apt-pinning.html