title: How can I build all Solution (.SLN) files under a directory
body: <p>We needed to automate testing that all of the C#, C++, &amp; VB.NET samples we ship compile properly. We need it to build all files without our listing each one. Listing each one means if someone forgets to add a new one (which will happen someday), explicit calls will miss it. By walking all .sln files, we always get everything.</p>
  
  <p>Doing this is pretty easy:</p>
  
  <ol>
  <li>Install the samples on a clean VM (that we revert back to the snapshot for each test run). </li>
  <li>Create a BuildAll.proj (MSBuild) file that calls all the .sln files installed. </li>
  <li>Use MSBuild to run the generated BuildAll.proj file</li>
  </ol>
  
  <p>Step 2 requires a means to generate the BuildAll.proj file. Is there any way to tell MSBuild to run all .sln files under a sub-directory or to create a BuildAll.proj that calls all the underlying .slnl files?</p>