powershell variable into where-object does not return data

Question

I am writing a script to ultimately check a block of servers for a certificate by FriendlyName and then go back and delete them once confirmed. Right now I am just trying to get the initial check to work. Currently it is not returning any data. Can anyone help?

$ContentsPath = "C:\Servers.txt"
$Servers = Get-Content $ContentsPath
$CertDeletionFile = "C:\CertsDeleted.csv"
$Today = Get-Date

$Certificate = Read-Host -Prompt "What certificate would you like to 
REMOVE?"
write-host $Certificate

function findCert {
param ([string]$Certificate)
Invoke-Command -ComputerName $Servers -ScriptBlock {Get-Childitem -Path 
Cert:LocalMachine\My | where {$_.friendlyname -eq $Certificate } | Select- 
Object -Property FriendlyName }
}
findCert

findCert -> findCert -Certificate $certificate on the last line - otherwise the findCert function will be comparing the friendlyName to an empty string — Mathias R. Jessen
– Mathias R. Jessen, Commented Jul 18, 2018 at 22:09

TessellatingHeckler · Accepted Answer · 2018-07-18 22:21:17Z

1

As Mathias R. Jessen comments, your findcert function needs a certificate name as a parameter, and you aren't passing anything when you call it, so it won't run properly.

You're also trying to use a local computer variable $Certificate, on a remote computer inside an invoke-command, and the remote computer can't get to that variable across the remoting.

I've rewritten it, with $using: which is a syntax that tells PS to send the value over the remoting session, and with renamed variables so it's more clear which part is accessing which variables:

$ContentsPath = 'C:\Servers.txt'
$Servers = Get-Content -LiteralPath $ContentsPath
$CertDeletionFile = 'C:\CertsDeleted.csv'
$Today = Get-Date

$typedCertificateName = Read-Host -Prompt "What certificate would you like to 
REMOVE?"
write-host $typedCertificateName

function findCert {
    param ([string]$Certificate)

    Invoke-Command -ComputerName $Servers -ScriptBlock {

        Get-Childitem -Path  Cert:LocalMachine\My |
            where-Object {$_.friendlyname -eq $using:Certificate } |
            Select-Object -Property FriendlyName
    }
}

findCert -Certificate $typedCertificateName

answered Jul 18, 2018 at 22:21

TessellatingHeckler

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2 Comments

Fixxer Over a year ago

TessellatingHeckler, I tried to look up the $using syntax and got this:learn.microsoft.com/en-us/powershell/module/…, which doesn't seem to be what you used. Can you tell me where I might find more info on this solution, as I haven't quite wrapped my head around it entirely? Thanks.

TessellatingHeckler Over a year ago

I'm glad :) About using: I just found this; apparently it's called the "Using scope modifier", and is documented here - learn.microsoft.com/en-gb/powershell/module/… - under "using local variables" section

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