Finding PowerShell Default Variables (Part 2)

by Jul 11, 2017

In the previous tip we explained how you can use a separate new and fresh PowerShell to retrieve all default variables. When you examine these variables closely, you will discover that still some PowerShell variables are missing.

Here is a slightly modified version called Get-BuiltInPSVariable that includes all reserved PowerShell variables:

function Get-BuiltInPSVariable($Name='*')
  # create a new PowerShell
  $ps = [PowerShell]::Create()
  # get all variables inside of it
  $null = $ps.AddScript('$null=$host;Get-Variable') 
  $ps.Invoke() |
    Where-Object Name -like $Name
  # dispose new PowerShell

To not miss out on any built-in PowerShell variable, this approach uses AddScript() instead of AddCommand(), and issues more than one command. Some PowerShell variables are created only after at least one command has run.

You can now dump all PowerShell built-in variables, or search for selected:

PS> Get-BuiltInPSVariable -Name *pref*

Name                           Value                                                                         
----                           -----                                                                         
ConfirmPreference              High                                                                          
DebugPreference                SilentlyContinue                                                              
ErrorActionPreference          Continue                                                                      
InformationPreference          SilentlyContinue                                                              
ProgressPreference             Continue                                                                      
VerbosePreference              SilentlyContinue                                                              
WarningPreference              Continue                                                                      
WhatIfPreference               False   

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