Specify assembly version number as a command line argument in MSBuild

The top answer is great, but I needed to make a few adjustments. We have a solution containing a mix of SDK and non-SDK projects. Further we also use AspNetCompileMerge for pre-compiling ASP.NET MVC 5 views. Using the property name AssemblyAttributes causes the target of GenerateAssemblyInfo from AspNetCompileMerge.targets to be executed and failing. So I finally arrived on the following target that is shared by the whole solution through Directory.Build.props:

<PropertyGroup>
    <Version Condition="'$(Version)' == ''">1.0.0.0</Version>
    <AssemblyVersion Condition="'$(AssemblyVersion)' == ''">$(Version.Split('-')[0])</AssemblyVersion>
    <FileVersion Condition="'$(FileVersion)' == ''">$(Version.Split('-')[0])</FileVersion>
    <InformationalVersion Condition="'$(InformationalVersion)' == ''">$(Version)</InformationalVersion>
</PropertyGroup>
<Target Name="NonSdkGenerateAssemblyInfo" DependsOnTargets="PrepareForBuild" BeforeTargets="BeforeBuild" Condition="('$(UsingMicrosoftNETSdk)' != 'True' And '$(GenerateAssemblyInfo)' != 'False')">
    <ItemGroup>
        <NonSdkAssemblyAttributes Include="AssemblyVersion">
            <_Parameter1>$(AssemblyVersion)</_Parameter1>
        </NonSdkAssemblyAttributes>
        <NonSdkAssemblyAttributes Include="AssemblyFileVersion">
            <_Parameter1>$(FileVersion)</_Parameter1>
        </NonSdkAssemblyAttributes>
        <NonSdkAssemblyAttributes Include="AssemblyInformationalVersion">
            <_Parameter1>$(InformationalVersion)</_Parameter1>
        </NonSdkAssemblyAttributes>
    </ItemGroup>
    <WriteCodeFragment AssemblyAttributes="@(NonSdkAssemblyAttributes)"
                       Language="C#"
                       OutputDirectory="$(IntermediateOutputPath)"
                       OutputFile="AssemblyInfo.cs">
        <Output TaskParameter="OutputFile" ItemName="Compile" />
        <Output TaskParameter="OutputFile" ItemName="FileWrites" />
    </WriteCodeFragment>
</Target>

You can add additional attributes if needed. The default version number is 1.0.0.0 and you can specify additional version numbers on the command line, mimicking SDK-behaviour:

• AssemblyVersion and FileVersion default to the value of $(Version) without the suffix. For example, if $(Version) is 1.2.3-beta.4, then the value would be 1.2.3.
• InformationalVersion defaults to the value of $(Version).

For SDK-style projects that are built using dotnet.exe, assembly version attributes are generated automatically, so you can use /p:Version=5.4.3.0 right out of the box.

If you use the old project format, you need to add the following BeforeBuild step to your .csproj file. No need to use extra .targets and extension packs, because MSBuild already has a nice built-in task which does most of the stuff:

<Target Name="BeforeBuild">
  <ItemGroup>
    <AssemblyAttributes Include="AssemblyVersion">
      <_Parameter1>$(Version)</_Parameter1>
    </AssemblyAttributes>
  </ItemGroup>
  <MakeDir Directories="$(IntermediateOutputPath)" />
  <WriteCodeFragment Language="C#"
                     OutputFile="$(IntermediateOutputPath)Version.cs"
                     AssemblyAttributes="@(AssemblyAttributes)" />
  <ItemGroup>
    <Compile Include="$(IntermediateOutputPath)Version.cs" />
  </ItemGroup>
</Target>

Just make sure you remove the existing AssemblyVersion attribute because it will now be generated during build.

Update 7/29/2020: Michael Parker has pointed out that if you use this approach and do a build from Visual Studio, you end up with an empty version in the Version.cs file. To overcome this, I suggest defining the default Version value in your .csproj or Directory.Build.props file as follows:

<PropertyGroup>
  ...
  <Version Condition="'$(Version)' == ''">1.0.0.0</Version>
</PropertyGroup>

This will set it to 1.0.0.0 if Version wasn't specified in the command line.

I know this is an old question but Google leads me to here as top result.

I followed a simple solution in this. No need for extension pack.

Basically what you need to do is add a "BuildCommon.targets" files and modify your csproj file accordingly to have the version number specified in msbuild like:

msbuild.exe abc.sln /p:Configuration=Release;VersionAssembly=1.2.3.4

Hope this helps.

I use the AssemblyInfo task as you describe in your comment all the time.

  <!-- update standard assembly attribute in all projects -->
  <Target Name="BeforeBuild" >
    <Message Text="Updating AssemblyInfo to Version $(VersionNumber)"></Message>
    <Message Text="Writing to AssemblyInfo files in $(SolutionRoot)"></Message>
    <AssemblyInfo AssemblyInfoFiles="@(AssemblyInfoFiles)" 
                  AssemblyCopyright="$(AssemblyCopyright)" 
                  AssemblyVersion="$(VersionNumber)"
                  AssemblyFileVersion="$(VersionNumber)"
                  >
    </AssemblyInfo>
  </Target>

The VersionNumber value is passed from outside the MSBuild project file exactly as you describe:

  MSBuild <project_file> /p:VersionNumber=<value>;...

We use the BeforeBuild target to ensure the AssemblyInfo.cs files all get worked on before the build starts. Is this not what you want?