Variable provider
PowerShell includes a provider and a drive, which allows variables to be listed, created, and changed using Get-ChildItem, Test-Path, and so on.
Get-ChildItem may be used to list all the variables in the current scope by running the command shown as follows:
Get-ChildItem variable:
    The first few variables returned by the command above are shown below. This is the same output as would be seen with Get-Variable:
Name                           Value
----                           -----
?                              True
^                              if
$                              }
args                           {}
ConfirmPreference              High
DebugPreference                SilentlyContinue
    The output shown includes the built-in variables, user-created variables, and any added modules that might have been imported.
As the provider behaves much like a filesystem, Test-Path may be used to determine whether a variable exists. Get-Variable...