title: How do I update BuildNumber using PowerShell
body: <p>I would like to update the Build.BuildNumber variable from a PowerShell script as a build step.</p>
  <p>I've tried:</p>
  <pre><code>Write-Host &quot;##vso[task.setvariable variable=BUILD_BUILDNUMBER]1.2.3.4&quot;
  </code></pre>
  <p>and</p>
  <pre><code>Write-Host &quot;##vso[task.setvariable variable=Build.BuildNumber]1.2.3.4&quot;
  </code></pre>
  <p>This has not worked.</p>