Get SharePoint Local Server Admins

if ( (Get-PSSnapin -Name Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue) -eq $null ) {
    Add-PSSnapin Microsoft.SharePoint.Powershell
}
$scriptBase = split-path $SCRIPT:MyInvocation.MyCommand.Path -parent
Set-Location $scriptBase
$global:timerServiceName = "SharePoint 2010 Timer"
$global:timerServiceInstanceName = "Microsoft SharePoint Foundation Timer"
# Get the local farm instance
[Microsoft.SharePoint.Administration.SPFarm]$farm = [Microsoft.SharePoint.Administration.SPFarm]::get_Local()

Function GetServerAdministrators([Microsoft.SharePoint.Administration.SPFarm]$farm)
{

 write-host ""
 write-host "Preparing to collect SP server administrator details" -fore magenta

 $output = $scriptbase + "\" + "ServerAdminDetails.csv"
 "ServerName" + "," + "AdminMember"  | Out-File -Encoding Default -FilePath $Output;

 foreach($server in $farm.Servers)
     {
  foreach($instance in $server.ServiceInstances)
          {

                if($instance.TypeName -eq $timerServiceInstanceName)
   {
                 [string]$serverName = $server.Name
    write-host "Collecting administrator details for the server " $servername -fore yellow
    $admins = invoke-command {net localgroup administrators | where {$_ -AND $_ -notmatch "command completed successfully"} | select -skip 4} -computer $serverName
    foreach($admin in $admins)
    {
     write-host $admin " is member of administrator group in server " $serverName -fore cyan
     $serverName + "," + $admin | Out-File -Encoding Default  -Append -FilePath $Output;
    }
    write-host "Administrator details for the server " $serverName " has been collected" -fore green
   }
  }
 }
 Write-host "Administrator details collected for all the SP servers in the farm" -fore green

}

GetServerAdministrators