:~$ apt-cache policy xorg
xorg:
  Installato: 1:7.7+1ubuntu8.1
  Candidato:  1:7.7+7ubuntu4
  Tabella versione:
     1:7.7+7ubuntu4 0
        500 http://it.archive.ubuntu.com/ubuntu/ vivid/main amd64 Packages
 *** 1:7.7+1ubuntu8.1 0
        100 /var/lib/dpkg/status