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PowerShell Tips and Quirks

There are a ton of PowerShell tips online, here I’ve collected the ones where I will probably forget about and need to reference. Please add some more in the comments section if you have a good tip.

Filtering with ‘where’

Here, we are only selecting the Id.

PS C:\Users\amb12> Get-Process | where { $_.ProcessName -eq 'cmd' } | select Id

   Id
   --
24552
30828

Search online for “Powershell comparison operators” to see how to use the other ones like -like -match -contains -is. Official docs

If you want to write your own cmdlets that accept piped input works, see the section called “accepting piped input”.

Looping with % (foreach)

Let’s say you don’t want the heading ‘Id’, you can use a foreach loop:

PS C:\Users\amb12> Get-Process | where { $_.ProcessName -eq 'cmd' } | %{$_.Id}
24552
30828

Get Object Type

Everything being returned is a “PSObject” in C# (think of it as a dictionary). If you want to see the actual type, call GetType() on the object.

PS C:\Users\amb12> (new-object System.Net.WebClient).GetType()

IsPublic IsSerial Name       BaseType
-------- -------- ----       --------
True     False    WebClient  System.ComponentModel.Component

View All Properties

If you want to see the full properties, add a | fl * (format list) at the end of the object.

PS C:\Users\amb12> (new-object System.Net.WebClient).GetType() | fl *
Module                     : System.dll
Assembly                   : System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
TypeHandle                 : System.RuntimeTypeHandle
DeclaringMethod            :
BaseType                   : System.ComponentModel.Component
UnderlyingSystemType       : System.Net.WebClient
FullName                   : System.Net.WebClient
...

Get Cmdlet Source

You use the Get-Command cmdlet, with the full name of the cmdlet you wish to get the source for (not the alias). Then get the .DLL property:

PS C:\Users\ambrose> (Get-Command get-content).DLL

C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\
Microsoft.PowerShell.Commands.Management\
...\Microsoft.PowerShell.Commands.Management.dll

This will work for cmdlets implemented in C#. You have to open the dll in ILSpy and find the implementation manually (by convention, the name is part of the method e.g. GetContentCommand)

If the cmdlet is implemented in PowerShell (e.g. Add-PrinterDriver), use .Scriptblock.

PS C:\Users\ambrose> (Get-Command Add-PrinterDriver).ScriptBlock

    [CmdletBinding(SupportsShouldProcess=$true, ConfirmImpact='Medium', PositionalBinding=$false)]


    param(

By looking at the name of a command, there is no way to know whether the cmdlet is implemented in C# or in PowerShell. You can use the .CommandType property to tell.

PS C:\Users\ambrose> (get-command get-content).CommandType
Cmdlet <--this means implemented in C# (dll)
PS C:\Users\ambrose> (get-command Add-PrinterDriver).CommandType
Function <--this means Powershell

Reserved variable names

Do not use these as variable names - PowerShell will not complain if you do, however you’ll just see weird results (variable names are case insensitive)

$input
$home

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