Futzing With System Variables

$Env:PATH is a common bane - you have a hundred machines, and you end up with fifty different $Env:PATH values.  Here's a quick way to audit them, and to set them remotely.  But be careful: just like with superpowers, this comes with great responsibility.

 

function Get-SystemVariable {
     param (
         [Parameter(  
             Position = 0,   
             ValueFromPipeline = $true,  
             ValueFromPipelineByPropertyName = $true  
         )][String[]]$ComputerName = @(),
         [Parameter( Position = 1 )][string]$Name
     );
    
     process {
         if (!$Name) { Out-Error "-name not specified.  Required."; }
         foreach ($computer in $ComputerName) {
             $wmi = Get-WmiObject -ComputerName $computer -Query "SELECT * FROM Win32_Environment WHERE username='<system>'";
             $computer | Select-Object -Property @{
                 n = 'ComputerName';
                 e = { $_; }
             }, @{
                 n = $name.ToUpper();
                 e = { ($wmi | ? { $_.Name -eq $name }).VariableValue; }
             }
         }
     }
}

function Set-SystemVariable {
     param (
         [Parameter(
             Position = 0,   
             ValueFromPipeline = $true,  
             ValueFromPipelineByPropertyName = $true  
         )][String[]]$ComputerName = @(),
         [Parameter( Position = 1 )][string]$Name,
         [Parameter( Position = 2 )][string]$Value
     );
    
     process {
         if (!$Name) { Out-Error "-name not specified.  Required."; }
         if (!$Value) { Out-Error "-value not specified.  Required."; }
         foreach ($computer in $ComputerName) {
             $temp = (Get-SystemVariable -ComputerName $computer -Name $Name).$Name
             SetX.exe -s $computer -m $Name $Value | Out-Null
             Get-SystemVariable -ComputerName $computer -Name $Name | Select-Object -Property *, @{
                 n = 'OldValue';
                 e = { $temp; }
             }
         }
     }
}