Help with PS Get-Random command

mattwestern · 2021-12-22T00:57:20.000Z

Hello.

I’m using this to rename PCs with:

$ServiceTAG = “B311-$(”$env:computername$(get-random)“)”
$OLDNAME = (Get-WmiObject win32_COMPUTERSYSTEM).Name
Rename-Computer -ComputerName $OLDNAME -NewName $ServiceTAG -force -restart

But I’m finding it’s leaving first 8-10 characters of the old name the same, so I end up with a lot of PC names with very similar looking netBIOS names.

I have very limited PS knowledge & I’m hoping someone can help me change the script so it will completely delete the old name, create a new randomized one and append that B311- to the beginning of the new name.

The netBIOS name limitation is 15 characters, so 15 minus B311- leaves us with ten characters to randomize.

Thanks for any help.

Neally · 2021-12-22T01:38:09.000Z

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Neally Bot

Neally · 2021-12-22T02:55:47.000Z

Without parameters or input, a Get-Random command returns a randomly selected 32-bit unsigned integer between 0 (zero) and Int32.MaxValue (0x7FFFFFFF, 2,147,483,647).

learn.microsoft.com

Get-Random (Microsoft.PowerShell.Utility) - PowerShell

The Get-Random cmdlet gets a randomly selected number. If you submit a collection of objects to Get-Random, it gets one or more randomly selected objects from the collection. Without parameters or input, a Get-Random command returns a randomly...

the way you have your code it does always add the old name

"B311-$("$env:computername$(get-random)")"

^ “B311-OLDNAME123456789”

Since ‘get-random’ spits a random number between 0 and ~2 mil out, that number can be less than 10 digits.

to account for that we can pad it, if the string is less than 15 characters long.

Do you want letters in it or are random numbers fine?

Also, I’d HIGHLY suggest, while the number is random, to check first if the name already exists in AD.

e.g.

# https://lazywinadmin.com/2013/10/powershell-get-domaincomputer-adsi.html
Function Get-Computer {
    [CmdletBinding()]
    PARAM(
        [Parameter(
            ValueFromPipelineByPropertyName = $true,
            ValueFromPipeline = $true,
            Mandatory = $true)]
        [String[]]$ComputerName
    )
    PROCESS {
        FOREACH ($item in $ComputerName) {
            $Search = [adsisearcher]"(&(objectCategory=Computer)(name=$item))"
            FOREACH ($Computer in $($Search.FindAll())) {
                New-Object -TypeName PSObject -Property @{
                    "Name"        = $($Computer.properties.name)
                    "DNShostName" = $($Computer.properties.dnshostname)
                    "Description" = $($Computer.properties.description)
                }
            }#foreach ($Computer in $($Search.FindAll
        }#FOREACH ($item in $ComputerName){
    }#PROCESS{
}#function Get-Computer

do{
    $NewName   = "B311-$(get-random)"

    if($NewName.Length -lt 15){
        $NewName = $NewName.PadRight(15,"$(0..9 | Get-Random)")
    }
    
    $checkName = $null
    $checkName = Get-Computer $NewName
    
    if($checkName){
        Write-warning "Name already exists in AD - trying again..." 
        $newNameFound = $false  
    }
    else{
        $newNameFound = $true
        $OLDNAME    = (Get-WmiObject win32_COMPUTERSYSTEM).Name
        Rename-Computer -ComputerName $OLDNAME -NewName $ServiceTAG -Force -Restart
    }
}
until (
    $newNameFound
)

mattwestern · 2021-12-22T03:51:46.000Z

Gee, thanks @alexw for the help, that’s a huge help.

I can use numbers & letters for the name. I can be pretty sure the name will be unique due to the B311- part.

If I wanted to not include the name duplication checking part, what would I include in my script for just the name generation?

Thanks once again.

Neally · 2021-12-22T06:53:18.000Z

something like so

$charSet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

$nameGen = 
for($i=0;$i -lt 10; $i++){
    $charset["$(0..35 | get-random)"]
}

$NewName   = "B311-$($nameGen -replace "\s")"
$OLDNAME    = (Get-WmiObject win32_COMPUTERSYSTEM).Name
Rename-Computer -ComputerName $OLDNAME -NewName $NewName -Force -Restar

mattwestern · 2021-12-23T05:52:26.000Z

Neally wrote:

something like so

$charSet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'

$nameGen = 
for($i=0;$i -lt 10; $i++){
    $charset["$(0..35 | get-random)"]
}

$NewName   = "B311-$($nameGen -replace "\s")"
$OLDNAME    = (Get-WmiObject win32_COMPUTERSYSTEM).Name
Rename-Computer -ComputerName $OLDNAME -NewName $NewName -Force -Restar

Gee, thanks that’s a very clever & great help.

Very much appreciated.

@alexw