The package management system on Ubuntu makes it extremely simple to install and remove packages, but sometimes it’s important to figure out what version of a particular package that you actually have installed.
The apt-get utilities are simply a front-end to the debian dpkg utility, which actually does the real work. You can use this utility to figure out what version is installed.
dpkg -s <packagename>
Here’s an example, where I was trying to figure out what version of Ruby I had installed on my system:
geek@ubuntuServ:~$ dpkg -s ruby1.8
Status: install ok installed
Maintainer: Ubuntu Core Developers <firstname.lastname@example.org>
Depends: libc6 (>= 2.4-1), libruby1.8 (>= 1.8.4)
Suggests: ruby1.8-examples, rdoc1.8, ri1.8
Description: Interpreter of object-oriented scripting language Ruby 1.8
Ruby is the interpreted scripting language for quick and easy
object-oriented programming. It has many features to process text
files and to do system management tasks (as in perl). It is simple,
straight-forward, and extensible.
This package provides version 1.8 series of Ruby.
On Debian, Ruby 1.8 is provided as separate packages. You can get
full Ruby 1.8 distribution by installing following packages.
ruby1.8 ruby1.8-dev ri1.8 rdoc1.8 irb1.8 ruby1.8-elisp
ruby1.8-examples libdbm-ruby1.8 libgdbm-ruby1.8 libtcltk-ruby1.8
Original-Maintainer: akira yamada <email@example.com>
You can see that I’ve got version 1.8.4 installed.