I want to adjust the output from my TeamCity build configuration of my class library so that the produced dll files have the following version number: 3.5.0.x, where x is the subversion revision number that TeamCity has picked up.

I've found that I can use the BUILD_NUMBER environment variable to get x, but unfortunately I don't understand what else I need to do.

The "tutorials" I find all say "You just add this to the script", but they don't say which script, and "this" is usually referring to the AssemblyInfo task from the MSBuild Community Extensions.

Do I need to build a custom MSBuild script somehow to use this? Is the "script" the same as either the solution file or the C# project file?

I don't know much about the MSBuild process at all, except that I can pass a solution file directly to MSBuild, but what I need to add to "the script" is XML, and the solution file decidedly does not look like XML.

So, can anyone point me to a step-by-step guide on how to make this work?

This is what I ended up with:

1. Install the MSBuild Community Tasks

2. Edit the .csproj file of my core class library, and change the bottom so that it reads:

   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Import Project="$(MSBuildExtensionsPath)\MSBuildCommunityTasks\MSBuild.Community.Tasks.Targets" />
   <Target Name="BeforeBuild">
     <AssemblyInfo Condition=" '$(BUILD_NUMBER)' != '' "
         CodeLanguage="CS"
         OutputFile="$(MSBuildProjectDirectory)\..\GlobalInfo.cs"
         AssemblyVersion="3.5.0.0"
         AssemblyFileVersion="$(BUILD_NUMBER)" />
   </Target>
   <Target Name="AfterBuild">
   

3. Change all my AssemblyInfo.cs files so that they don't specify either AssemblyVersion or AssemblyFileVersion (in retrospect, I'll look into putting AssemblyVersion back)

4. Added a link to the now global GlobalInfo.cs that is located just outside all the project
5. Make sure this file is built once, so that I have a default file in source control

This will now update GlobalInfo.cs only if the environment variable BUILD_NUMBER is set, which it is when I build through TeamCity.

I opted for keeping AssemblyVersion constant, so that references still work, and only update AssemblyFileVersion, so that I can see which build a dll is from.