Powershell - Using invoke-command in a for loop

Question

When i try to run invoke-command for every computer in Active-Directory , i will encounter the following error : "Invoke-Command : One or more computer names are not valid. If you are trying to pass a URI, use the -ConnectionUri parameter, or pass URI objects instead of strings. "

    ```
      $Hosts_Array=Get-ADComputer -Properties CN -Filter * | Sort-Object  | Select-Object CN
          foreach ($i in $Hosts_Array) {
                Invoke-Command -ComputerName $i -ScriptBlock { Get-Service -Name "sysmon64"} 
           }
    ```

I use the For loop to run the command for every computer that fetch from the AD.

`Select-Object` --> `Select-Object -ExpandProperty` or inside your loop use `-ComputerName $i.Name` — Theo, Aug 22 '21 at 12:01

Theo · Accepted Answer · 2021-08-23T09:01:33.863

As commented, Select-Object returns objects, in this case objects with just one property called 'CN'.

In fact, you don't need to ask for the CN at all, because Get-ADComputer returns these properties by default: DistinguishedName, DNSHostName, Enabled, Name, ObjectClass, ObjectGUID, SamAccountName, SID, UserPrincipalName

You can simplify your code by doing:

$Hosts_Array = (Get-ADComputer -Filter *).Name | Sort-Object
foreach ($computer in $Hosts_Array) {
    Invoke-Command -ComputerName $computer -ScriptBlock { Get-Service -Name "sysmon64" } 
}

(Get-ADComputer -Filter *).Name returns a string array of just the computer names, which can also be done using Get-ADComputer -Filter * | Select-Object -ExpandProperty Name

P.S. I have changed the variable name to iterate with from $i (usually used in numbered loops) into $computer to make it clearer

^{Each object in AD has a Relative Distinguished Name (RDN). This is the name of the object in it's parent OU/Container. For user, group, computer, and container objects, the RDN is the value of the cn attribute (Common Name). For OU objects, the RDN is the value of the ou attribute. For domain component objects, it's the dc attribute.

The Name property returns the RDN of any object.}

It works . Thank you but i just got confused what is the problem with CN instead of Name ? when i echo CN it returns strings like computer name exactly . So how CN differs from Name while both are same in characters and structure ? — Seyed Muhammad Alavi, Aug 23 '21 at 05:17
@SeyedMuhammadAlavi Each object in AD has a `Relative Distinguished Name` (RDN). This is the name of the object in it's parent OU/Container. For user, group, computer, and container objects, the RDN is the value of the `cn` attribute (Common Name). For OU objects, the RDN is the value of the `ou` attribute. For domain component objects, it's the `dc` attribute. The `Name` property returns the RDN of any object. You could indeed use `CN` in your code, but that would require you to ask for this extra property where there is really no need to. — Theo, Aug 23 '21 at 08:54

score 0 · Answer 2 · answered Aug 22 '21 at 12:01

What happens if you place invoke-command into try/catch block?

$Hosts_Array=Get-ADComputer -Properties CN -Filter * | Sort-Object  | Select-Object CN
    foreach ($i in $Hosts_Array) {
        try{
            Invoke-Command -ComputerName $i -ScriptBlock { Get-Service -Name "sysmon64"}
        }
        catch{
            write-output("Unable to resolve $i ")
        }
    }

score 0 · Answer 3 · answered Aug 22 '21 at 13:30

I would not use invoke-command, as Get-Service can be used to connect to computers remotely.

If you prefer to use get-service, then you can try the following script:

$Hosts_Array = Get-ADComputer -Properties * -Filter *

$Obj = @()
$ServiceName = "sysmon64"
foreach ($Computer in $Hosts_Array) 
{
    $Hostname = $computer.name
    
    # Check if computer is online
    write-host "pinging $Hostname" -for Cyan
    $ping = Test-Connection $Hostname -Count 1 -Quiet

    if ($ping)
    {
        write-host "Computer found - $Hostname" -ForegroundColor Green
        $Service = $null
        $Service = Get-Service $ServiceName -ComputerName $Hostname -ErrorAction SilentlyContinue

        if ($ServiceName)
        {
            write-host "Service $ServiceName found - $Hostname" -ForegroundColor Green
            # create a hash table to store the date
            $Hash = @{
                Hostname = $Hostname
                ServiceName = $Service.Name
                Displayname = $Service.DisplayName
                Status = $Service.Status
            }

            $Obj += New-Object psobject -Property $hash
        }
        else
        {
            write-host "Service NOT $ServiceName found - $Hostname" -ForegroundColor red
        }
        
    }
    else
    {
    write-host "Computer found - $Hostname" -for Red
    }
}

$Obj

score 0 · Answer 4 · answered Aug 22 '21 at 13:50

This is probably the most common powershell question. Dereference the CN property into a string with foreach or select -expand or .CN and it will work. I would run the whole list at once so it runs in parallel.

$hosts_array = Get-ADComputer -Properties CN -Filter * | Sort-Object |
  foreach-object CN
invoke-command $hosts_array { get-service sysmon64 }

Powershell - Using invoke-command in a for loop

4 Answers4

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