Demonstrates how you can convert a relative path to an absolute path in MSBuild

get-full-path.proj

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" DefaultTargets="Demo">

  <!-- Demonstrates how you can convert a relative path to a full path in MSBuild -->
  
  <PropertyGroup>
    <Filepath>sample\file.txt</Filepath>
  </PropertyGroup>
  
  <Target Name="Demo">
    <PropertyGroup>
      <_FullPath>$([System.IO.Path]::GetFullPath($(Filepath)))</_FullPath>
    </PropertyGroup>

    <Message Text="Fullpath: '$(_FullPath)'" Importance="high"/>
    
  </Target>  
</Project>