search for files within Debian packages (command-line interface)

 apt-file is a command line tool for searching files contained in packages
 for the APT packaging system. You can search in which package a file is
 included or list the contents of a package without installing or fetching it.
 If you would prefer not to download the large files used by apt-file you can
 run rapt-file, which calls a remote server to do the searches.