Hello again! Today I will share a small PowerShell function, ExpandEnvironmentVariables that I use to expand environment variables that are written in legacy syntax (%varname%). For instance, the function is useful if you read values from configuration text files that may contain variable names.

ExpandEnvironmentVariables supports PowerShell 1 and 2. It is designed to accept pipeline input and uses the ExpandEnvironmentVariables() method of the System.Environment class to resolve variables. The function supports nested variable references

function ExpandEnvironmentVariables {
	param (
		[string]$String
	)
	begin {
		function _exp ([string]$str) {
			$s1 = $str
			$s2 = [System.Environment]::ExpandEnvironmentVariables($s1)
			while ($s2 -ne $s1) {
				$s1 = $s2
				$s2 = [System.Environment]::ExpandEnvironmentVariables($s1)
			}
			$s2
		}
	}
	process {
		if ($_) {
			$String = $_
		} elseif (!$String) {
			throw 'No value for the String parameter specified.'
		}
		_exp -str $String
	}
}

About two weeks ago Citrix has released the XenApp 6 PowerShell SDK that enables people to manage XenApp 6 farms using Microsoft PowerShell scripting. The modules included in the SDK are Citrix XenApp Commands (aka XenApp cmdlets), Citrix Group Policy Provider, and Citrix Common Commands. The Citrix Principal Design Engineer Tom M Kludy wrote some nice blogs about the XenApp 6 SDK.

Reading the XenApp cmdlets reference I found the following information for those of you who are familiar with MFCOM:

Starting in XenApp 6.0, MFCOM as a publically supported programming and scripting interface will no longer be available. All existing MFCOM-based code no longer works on XenApp 6.0. No doubt that the absence of MFCOM will be something that requires additional effort to the adoption of XenApp 6.0.

Take a deep breath and don’t panic! Most of MFCOM scripts can be replaced by one-liners meaning that most of the short MFCOM scripts are obsolete as they’ve been replaced by PowerShell cmdlets.

For example adding a Citrix admin with the XenApp 6 PowerShell SDK is a one-liner:

New-XAAdministrator –AdministratorName ctxadmin –AdministratorType Full

In MFCOM, an administrator would need to write a script with dozens lines of code like below to accomplish the same task. So after all, it was definitely a good idea to discontinue MFCOM Support.

function Test-IsCitrixAdministrator(){

	$MetaFrameWinFarmObject = 1

	$MFCOM = New-Object -ComObject 'MetaframeCOM.MetaFrameFarm'
	if (!$MFCOM)
	{
		$result = $false
	}
	else
	{
		$MFCOM.Initialize($MetaFrameWinFarmObject)
		$result = [boolean] $MFCOM.WinFarmObject.IsCitrixAdministrator
		$MFCOM = $null
	}
	$result
}

function Test-ADGroup(){

	param(
		$name = $(throw "No AD group name specified.")
	)

	$domainRoot = [System.DirectoryServices.ActiveDirectory.Forest]::GetCurrentForest().RootDomain.Name
	$searcher = New-Object System.DirectoryServices.DirectorySearcher([ADSI]"GC://$domainRoot")
	$searcher.Filter = "(&(objectClass=Group)(name=$name))"
	$result = $searcher.FindOne()
	[boolean] $result
}

function Add-CitrixAdmins(){

	param(
		$accounts = $(throw "No comma-seperated list of Citrix Admin accounts specified."),
		$adminType = $(throw "No Admin Type specified. (Full or ViewOnly?)")
	)

	$MetaFrameWinFarmObject     = 1
	$MFAdminPermissionViewOnly  = 1
	$MFAdminPermissionFullAdmin = 3
	$MFAccountAuthorityADS      = 3
	$MFAccountGlobalGroup       = 4
	$MFAccountEnable            = 1

	switch($adminType)
	{
		"Full"
		{
			$MFAdminPermission = $MFAdminPermissionFullAdmin
		}

		"ViewOnly"
		{
			$MFAdminPermission = $MFAdminPermissionViewOnly
		}

		default
		{
			throw "This function supports only the Citrix Admin Privilege levels Full and ViewOnly."
		}
	}

	$MFCOM = New-Object -ComObject 'MetaframeCOM.MetaFrameFarm'
	$MFCOM.Initialize($MetaFrameWinFarmObject)

 	$currentAdmins = $MFCOM.Admins | %{$_.FriendlyName}
	$newAdmins     = $accounts.Split(",")

	$defaultDomain = $env:USERDOMAIN

	foreach($account in $newAdmins)
	{
		$newAdmin = $account.Split("\")
		if($newAdmin.Count -eq 1)
		{
			$accountDomain = $defaultDomain
			$accountName = $account
			if (-not (Test-ADGroup $accountName)){throw "Group does not exist in $accountDomain - $accountName"}
		}
		else
		{
			$accountDomain = $newAdmin[0]
			$accountName = $newAdmin[1]
		}

		if($currentAdmins -notcontains "$accountDomain\$accountName")
		{
			$mfAdmin = $MFCOM.AddAdmin()
			$mfAdmin.AdminType = $MFAdminPermission
			$mfAdmin.AAType = $MFAccountAuthorityADS
			$mfAdmin.AAName = $accountDomain
			$mfAdmin.AccountType = $MFAccountGlobalGroup
			$mfAdmin.AccountName = $accountName
			$mfAdmin.Enable = $MFAccountEnable
			$mfAdmin.SaveData()
			$mfAdmin = $null
		}
	}
}