title: select-string not taking variable in powershell
body: <p>I have stored a MAC address as a string in a variable:</p>
  
  <pre><code>$macaddress= "1234567"
  </code></pre>
  
  <p>I'm trying to store the output from a command in another variable:</p>
  
  <pre><code> $testing = { arp -a; | select-string  $macaddress }
   Write-Host $testing
  </code></pre>
  
  <p>If the command is executed in PowerShell, I do not see the value of <code>$macaddress</code>. It displays as a '$macaddress' in the screen instead of its value "1234567".</p>
  
  <p>Please help me set the value of <code>$macaddress</code> correctly.</p>