I can't get Powershell StartsWith function to work

Question

I'm trying to create a Powershell script that prints out only certain AD groups from the Folder Permission settings. However for some reason Powershell doesn't recognize StartsWith function.

("C:\folder" | get-acl).Access | ForEach-Object { if (($_.IdentityReference).StartsWith("sl_test")) { continue }; $_ }

When I run this I got errors similar to this for every foreach object:

Method invocation failed because [System.Security.Principal.NTAccount] does not contain a method named 'StartsWith'. At C:\\temp\\test.ps1:1 char:56 + ("C:\\folder" | get-acl).Access | ForEach-Object { if (($_.IdentityReference).St ... + ~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : InvalidOperation: (:) [], RuntimeException + FullyQualifiedErrorId : MethodNotFound

Any suggestions on how to get this to work?

Answer 1

IdentityReference is a [System.Security.Principal.NTAccount] according to your error message.

But .StartWith is a method on the String type. If you call a method, Powershell does no magic for you, AFAIK.

Try ... ($_.IdentityReference) -match "^sl_test" ... , which should do the implicit string conversion.

Answer 2

如果要使用IdentityReference的字符串表示形式（无论它是NTAccount对象还是SID），都可以引用Value属性：

$_.IdentityReference.Value.StartsWith('sl_test')

Answer 3

Try:

Get-Acl -Path "C:\folder" | Select-Object -ExpandProperty Access | Where-Object {$_.IdentityReference -like "sl_test*" }

You can customize the output with an additional | Select-Object -Property XY | Select-Object -Property XY