apt-cache policy packagename
retorna versões de um pacote disponíveis nos repositórios.
Exemplo:
$ apt-cache policy xserver-xorg-video-nouveau
xserver-xorg-video-nouveau:
Installed: 1:0.0.16+git20120113.b0d7f4dd-0ubuntu0sarvatt~oneiric
Candidate: 1:0.0.16+git20120113.b0d7f4dd-0ubuntu0sarvatt~oneiric
Version table:
*** 1:0.0.16+git20120113.b0d7f4dd-0ubuntu0sarvatt~oneiric 0
500 http://ppa.launchpad.net/xorg-edgers/ppa/ubuntu/ oneiric/main amd64 Packages
100 /var/lib/dpkg/status
1:0.0.16+git20110411+8378443-1 0
500 http://nl.archive.ubuntu.com/ubuntu/ oneiric/main amd64 Packages