ubuntu查看软件包版本
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.
Ubuntu上的软件包管理系统使安装和删除软件包变得极为简单，但是有时弄清楚您实际安装了哪个版本的特定软件包很重要。
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.
apt-get实用程序只是debian dpkg实用程序的前端，它实际上完成了实际工作。 您可以使用此实用工具来确定已安装的版本。
dpkg -s <packagename>
dpkg -s <软件包名称>
Here’s an example, where I was trying to figure out what version of Ruby I had install
