Get the active user using explorer.exe

Get-akActiveUser.ps1

Function Get-akActiveUser
{
	<#	
		.SYNOPSIS
			This function gets the activer user on specified computer.
		
		.DESCRIPTION
			This function gets the activer user on specified computer as defined by the running explorer process on their system. Potentially may return
            more than one user.
		
		.PARAMETER ComputerName
			The name of the computer to be used to determine the active user.
		
		.EXAMPLE
			Get-ActiveUser
            
            Get the active user(s) for the computer running PowerShell.
			
		.EXAMPLE
			Get-Content computers.txt | Get-ActiverUser

            Get the active user(s) for each computer on each line in the text file computers.txt

        .EXAMPLE
            Get-ADComputer -SearchBase "OU=SomeWhere,DC=contonso,DC=com" | Select -ExpandProperty Name | Get-akActiveUser

            Gets the active user(s) for each computer under the SomeWhere OU in ActiveDirectory.

	#>	
	[CmdletBinding()]
	param
	(
		[Parameter(Mandatory=$False,
		ValueFromPipeline=$True, ValueFromPipelinebyPropertyName=$true)][Alias('Name')]
		[string[]]$ComputerName = $env:COMPUTERNAME
	)
    Begin{}
	Process
	{
		ForEach($Computer in $ComputerName)
		{
            Write-Verbose "Connecting to WMI on $Computer"
			Try
			{
				$Processes = Get-WmiObject -class win32_process -ComputerName $Computer -filter "ExecutablePath like '%explorer.exe'" -ErrorAction Stop
			}
			Catch
			{
				Write-Error -Message "Could not connect to WMI Class Win32_Process on $Computer"
				Continue
			}
			$uid = @($Processes | Foreach-Object {$_.GetOwner().User}  | Where-Object {$_ -ne "NETWORK SERVICE" -and $_ -ne "LOCAL SERVICE" -and $_ -ne "SYSTEM"} | Sort-Object -Unique)
			If($uid -like "")
			{
				$props = @{ActiveUser="NA"
						   ComputerName=$Computer
				          }
			}
			else
			{
				$uid = ($uid | Out-String).TrimEnd()
				$props = @{ActiveUser=$uid
						   ComputerName=$Computer
						  }
			}
			New-Object -TypeName Psobject -Property $props
		}
	}
}