title: Update environment variables from TeamCity build step
body: <p>In my build configuration I have environment variables for major, minor and patch version numbers.</p>
  
  <p>I am trying to write a build step that checks the name of the branch and if it is a release branch with a higher version than the current env vars, I want to update them.</p>
  
  <p>I have tried setting the variables, but when I go the 'Parameters' tab it still shows the old value.</p>
  
  <p>I am writing a Powershell script, and have tried:</p>
  
  <p><code>Write-Host "##teamcity[setParameter name='major.version' value='2']"</code></p>
  
  <p><code>Write-Host "##teamcity[setParameter name='env.major.version' value='2']"</code></p>
  
  <p><code>$Env:major.version = 2</code></p>