Over the years, I have had to manage some client-facing servers that run Parallels Plesk on top of a Linux OS. I often need to see exactly what version and build number is running on the server. Using a shell, there are two ways to determine what version of Parallels Plesk is running.
The version file is a simple ASCII text file that has information on the currently running version of Plesk. In my case, the result looked like this:
10.3.1 CentOS 5 1013110726.09
rpm -q psa
This method queries the RPM database for the psa package, which is Parallels Plesk. In my case, the result looked like this: