$ apt-cache show <packagename>

$ sudo dpkg-query -L <packagename>

$ apt-cache policy elixir
elixir:
  Installed: 1.5.1-1
  Candidate: 1.5.1-1
  Version table:
  *** 1.5.1-1 500
        500 http://packages.erlang-solutions.com/ubuntu xenial/contrib amd64 Packages
        100 /var/lib/dpkg/status
      1.5.1-1 500
        500 http://packages.erlang-solutions.com/ubuntu xenial/contrib i386 Packages
      1.5.0-1 500
        500 http://packages.erlang-solutions.com/ubuntu xenial/contrib amd64 Packages
      1.5.0-1 500
        500 http://packages.erlang-solutions.com/ubuntu xenial/contrib i386 Packages

$ sudo updatedb
$ sudo locate <filename>

$ apt-cache search <packagename>

$ sudo dpkg-query -S <filename>

$ sudo apt update

$ sudo apt upgrade

$ sudo apt remove <packagename>

$ sudo apt remove <packagename>=<version>

$ sudo apt remove postgresql=10*

$ sudo apt [purge|remove --purge] <packagename>

$ sudo aptitude [remove|purge] <packagename>

$ sudo apt autoremove