Here are a couple of ways to tell which version of Ubuntu you’re running.
1. From the desktop, select System > About Ubuntu. Look at the top of the text for the sentence that starts, “Thank you for your interest in Ubuntu….” The rest of the sentence describes the version details. (This is broken on my system, which is why I ended up looking for other ways.)
2. From the desktop, select System > Administration > System Monitor. Click the “System” tab. This is comprehensive, and worked great.
3. From a terminal, use the command:
4. From a terminal, use the command:
Related: To print the kernel version use the command: