Monthly Archive


Monthly Archives: March 2018

Cmdlet parameters

I discovered another way to investigate cmdlet parameters.

If you dig into the output of Get-Command you’ll see it has a parameters property

PS> Get-Command Clear-RecycleBin | select parameters

{[DriveLetter, System.Management.Automation.ParameterMetadata], [Force, System.Management.Automation.ParameterMetada...

If you expand the parameters property:

PS> Get-Command Clear-RecycleBin | select -ExpandProperty  parameters

Key                 Value
---                 -----
DriveLetter         System.Management.Automation.ParameterMetadata
Force               System.Management.Automation.ParameterMetadata
Verbose             System.Management.Automation.ParameterMetadata
Debug               System.Management.Automation.ParameterMetadata
ErrorAction         System.Management.Automation.ParameterMetadata
WarningAction       System.Management.Automation.ParameterMetadata
InformationAction   System.Management.Automation.ParameterMetadata
ErrorVariable       System.Management.Automation.ParameterMetadata
WarningVariable     System.Management.Automation.ParameterMetadata
InformationVariable System.Management.Automation.ParameterMetadata
OutVariable         System.Management.Automation.ParameterMetadata
OutBuffer           System.Management.Automation.ParameterMetadata
PipelineVariable    System.Management.Automation.ParameterMetadata
WhatIf              System.Management.Automation.ParameterMetadata
Confirm             System.Management.Automation.ParameterMetadata

The really nice thing is that you get the common parameters listed as well.

If you want to dig into the individual parameters

PS> $params = Get-Command Clear-RecycleBin | select -ExpandProperty  parameters

PS> $params.DriveLetter

Name            : DriveLetter
ParameterType   : System.String[]
ParameterSets   : {[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}
IsDynamic       : False
Aliases         : {}
Attributes      : {__AllParameterSets, System.Management.Automation.ValidateNotNullOrEmptyAttribute}
SwitchParameter : False


PS> $params.Verbose

Name            : Verbose
ParameterType   : System.Management.Automation.SwitchParameter
ParameterSets   : {[__AllParameterSets, System.Management.Automation.ParameterSetMetadata]}
IsDynamic       : False
Aliases         : {vb}
Attributes      : {System.Management.Automation.AliasAttribute, __AllParameterSets}
SwitchParameter : True

You can see the parameter sets and aliases which is useful. The parameter type indicates the input data.

This is very useful where you haven’t installed the help files on a system

Finding special folders

Windows has a number of special folders. These can be accessed either directly through the file system – for example the Documents special folder is C:\<user>\Richard\Documents or through code. But how do you go about finding special folders.

The easiest way is to use this script

1..1000 |
ForEach-Object {
$shell = New-Object -ComObject Shell.Application
$sf = $shell.NameSpace($psitem)

if ($sf) {

$props = [ordered]@{
Value = $psitem
Name = $sf.Title
Path = $sf.Self.Path

New-Object -TypeName PSobject -Property $props

Looping through the values 1-1000 the Shell.Application COM object is used to find the namespace corresponding to that number. If it exists, the value, name and path are output.

In the Path property you’ll either get a normal looking path e.g. C:\Windows\System32 or something like this - ::{645FF040-5081-101B-9F08-00AA002F954E} - which is the CLSID or Windows Class Identifier