6.4.2 Information on a package

Search and display information from package archives. Make sure to point APT to the proper archive(s) by editing /etc/apt/sources.list. If you want to see how packages in testing/unstable do against the currently installed one, use apt-cache policy—quite nice.

     # apt-get   check           # update cache and check for broken packages
     $ apt-cache search  pattern # search package from text description
     $ apt-cache policy  package # package priority/dists information
     $ apt-cache show -a package # show description of package in all dists
     $ apt-cache showsrc package # show description of matching source package
     $ apt-cache showpkg package # package information for debugging
     # dpkg  --audit|-C          # search for partially installed packages
     $ dpkg {-s|--status} package ... # description of installed package
     $ dpkg -l package ...       # status of installed package (1 line each)
     $ dpkg -L package ...       # list filenames installed by the package

apt-cache showsrc is not documented as of the Woody release but works :)

You can also find package information in (I use mc to browse these):

     /var/lib/apt/lists/*
     /var/lib/dpkg/available

The comparison of the following files provides information on what exactly has happened in the last few install sessions.

     /var/lib/dpkg/status
     /var/backups/dpkg.status*