Here's how to check what version of a software package is available in the Ubuntu repositories
November 26, 2019
I needed to know which version of LXD was available in the official Ubuntu respository.
All that was needed was to issue the command (after running sudo apt update):
sudo apt-cache policy lxd
That's all you need to do to list what version is available for any package. Just replace lxd above with the name of the package you want to find the version of.