Can't access Environment Variable from Remote Server with PowerShell - powershell

Question

I have a script to query a list of remote windows servers to retrieve the value of an Environment Variable I have created.
I can see that the variable is indeed there because I can see it when I print all variables: $EnvObj:
try
{
$Name="MY_VAR"
$VerbosePreference="Continue"
# Read a list of server names
$file = New-Object System.IO.StreamReader -Arg "C:\Users\foo\Documents\test.txt"
while ($Computer = $file.ReadLine())
{
if(!(Test-Connection -ComputerName $Computer -Count 1 -quiet))
{
Write-Verbose "$Computer is not online"
Continue
}
try
{
$EnvObj = #(Get-WMIObject -Class Win32_Environment -ComputerName $Computer -EA Stop)
if(!$EnvObj)
{
Write-Verbose "$Computer returned empty list of environment variables"
Continue
}
if($Name)
{
Write-Verbose "Looking for environment variable with the name $name"
$Env = $EnvObj | Where-Object {$_.Name -eq $Name}
# None of these work but printing $EnvObj shows that $Name ("MY_VAR") is there:
$res=[environment]::GetEnvironmentVariable($Name, "Process")
$res1=[environment]::GetEnvironmentVariable($Name, "User")
$res2=[environment]::GetEnvironmentVariable($Name, "Machine")
$res4=$Env:Name
if(!$Env)
{
Write-Verbose "$Computer has no environment variable with name $Name"
Continue
}
}
else
{
Write-Verbose "No environment variable specified. Listing all"
$EnvObj # shows that the requested environment variable is present
}
}
catch
{
Write-Verbose "Error occurred while querying $Computer. $_"
Continue
}
}
}
finally
{
$file.close()
}
The variable itself is owned by <SYSTEM>:
VariableValue Name UserName
------------- ---- --------
1234 MY_VAR <SYSTEM>
But when I try to retrieve it with any of the possible enumerations, it just returns nothing:
None of these work but printing $EnvObj shows that $Name ("MY_VAR") is there:
# .Net way
$res=[environment]::GetEnvironmentVariable($Name, "Process")
$res1=[environment]::GetEnvironmentVariable($Name, "User")
$res2=[environment]::GetEnvironmentVariable($Name, "Machine")
# PS Way
$res4=$Env:Name
... even though when I print the $EnvObj object I can see that $Name is definitely there.
What is wrong?

Answer 1

Your line
$EnvObj = #(Get-WMIObject -Class Win32_Environment -ComputerName $Computer -EA Stop)
Will return an array of [ManagementObject].
To examine all the properties you can pipe one of these objects to Get-Member
$EnvObj[0] | Get-Member
TypeName: System.Management.ManagementObject#root\cimv2\Win32_Environment
Name MemberType Definition
---- ---------- ----------
PSComputerName AliasProperty PSComputerName = __SERVER
Caption Property string Caption {get;set;}
Description Property string Description {get;set;}
InstallDate Property string InstallDate {get;set;}
Name Property string Name {get;set;}
Status Property string Status {get;set;}
SystemVariable Property bool SystemVariable {get;set;}
UserName Property string UserName {get;set;}
VariableValue Property string VariableValue {get;set;}
__CLASS Property string __CLASS {get;set;}
__DERIVATION Property string[] __DERIVATION {get;set;}
__DYNASTY Property string __DYNASTY {get;set;}
__GENUS Property int __GENUS {get;set;}
__NAMESPACE Property string __NAMESPACE {get;set;}
__PATH Property string __PATH {get;set;}
__PROPERTY_COUNT Property int __PROPERTY_COUNT {get;set;}
__RELPATH Property string __RELPATH {get;set;}
__SERVER Property string __SERVER {get;set;}
__SUPERCLASS Property string __SUPERCLASS {get;set;}
PSStatus PropertySet PSStatus {Status, Name, SystemVariable}
ConvertFromDateTime ScriptMethod System.Object ConvertFromDateTime();
ConvertToDateTime ScriptMethod System.Object ConvertToDateTime();
From this you can see that the value property is called VariableValue.
So,
$EnvLookup = $EnvObj | Where-Object {$_.Name -eq $Name}
$res = $EnvLookup.VariableValue