Find next available computer name - powershell

Question

I'm trying to find the next available computer name in out domain. Our computers use a naming format
departmentName001
departmentName003
departmentName004
...
departmentName999
I can find the existing computer accounts and add 1 but I can't work out for to get it to start looking at 001, I'm aware of the use of "{0:d3}" -f but I'm not using it correctly. Can anyone help?
function GetComputerList($ComputerName)
{
$objSearcher = New-Object System.DirectoryServices.DirectorySearcher
$objSearcher.SearchRoot = “LDAP://dc=domain,dc=local”
$objSearcher.Filter = ("(&(objectCategory=computer)(name=$ComputerName))")
$colProplist = "name"
$objSearcher.PageSize = 1000
foreach ($i in $colPropList){[void]$objSearcher.PropertiesToLoad.Add($i)}
$colResults = $objSearcher.FindAll()
foreach ($objResult in $colResults)
{$objComputer = $objResult.Properties; $objComputer.name}
}
$HostName = Finance
$unit="{0:d3}" -f $_
$num = GetComputerList("$HostName*") | Foreach {[int]($_.Name)} | Sort-Object | Select-Object -Last 1
$name = $HostName+($unit+($num+1))

Answer 1

Try this, it gets all computer with name starting with 'departmentName', strips all a-z characters, leaving just the numbers, converts the numbers to integers and sorting them to find the largest one:
$searcher = [ADSISearcher]'(&(objectCategory=computer)(name=departmentName*))'
$searcher.PageSize = 1000
$last = $searcher.FindAll() | Foreach-Object { [int]($_.Properties.name -replace '\D').Trim() } | Sort-Object | Select-Object -Last 1
$digitLength = "$last".Length
$NewComputerName = "{0}{1:D$digitLength}" -f 'departmentName',($last+1)
$NewComputerName
EDIT:
# get next available number in a range of numbers. returns 5 for 1,2,3,4,6,7,9
$number = $searcher.FindAll() | Foreach-Object { [int]($_.Properties.name -replace '\D').Trim() } | Sort-Object
for($i=0; $i -lt $number.length; $i++) {if( $number[$i+1]-$number[$i] -gt 1) {$number[$i]+1; break} }

Answer 2

try this:
$searcher = [ADSISearcher]'(&(objectCategory=computer)(name=Finance*))'
$searcher.PageSize = 1000
$last = $searcher.FindAll() | Foreach-Object {
[string]($_.Properties.name -replace '\D') } | Sort-Object
$i = 0
$last | % { if ($i -ne [int]$_ ) { $new = $i.tostring().padleft(3,'0'); break }
else
{ $i++ }}
$newComputerName = "finance" + $new

Answer 3

based on the information in this post I have made a few changes and tweaks to the code for my environment to check more than just AD.. and also fixed it not filling in blanks at the start of a range.. I have blogged it here: AutoGeneratingServer Names
copy of the code here too, and I know it can be refactored lots!
[CmdletBinding()]
param()
# ********************************************************
$startOfName = "xxxYYYZZWEB"
# ********************************************************
# VMWare Details
$ADVIServers = #("vsphere1.blah.local","vsphere2.blah.local","vsphere3.blah.local","vsphere4.blah.local")
$StandAloneHosts = #()
# DNS Details
$DNSServer = "xxxxxx.blah.local"
# SCCM 2012 Details
$SCCM2012SiteServer = "sccm2012.blah.local"
$SCCM2012SiteCode = 'SiteCode'
# SCCM 2007 Details
$SCCM2007SiteServer = "sccm2007.blah.local"
$SCCM2007SiteCode = 'SiteCode2'
# SCOM 2007 Details
$SCOMServer = "scom.blah.local"
# Create Empty Arrays
$VMNumbers = #()
$ADnumbers = #()
$DNSNumbers = #()
$SCCM2012Numbers = #()
$SCCM2007Numbers = #()
$SCOM2007Numbers = #()
# VMWare
Write-Verbose "Processing VMware"
Add-PSSnapin vmware.vimautomation.core -ErrorAction SilentlyContinue
# Set options for certificates and connecting to multiple enviroments
$null = Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -Confirm:$False
$null = Set-PowerCLIConfiguration -DefaultVIServerMode Multiple -Scope User -Confirm:$False
# Connect to each AD Authenticated viServer
foreach ($VIServer in $ADVIServers){$null = Connect-VIServer $VIServer -verbose:$false}
# Connect to standalone host
foreach ($Host in $StandAloneHosts){$null = Connect-VIServer $Host -User 'usernamehere' -Password 'passwordhere' -verbose:$false}
# get next available number in a range of numbers.
$VMNames = Get-VM -Name "$($startOfName)*" -verbose:$false |select Name
$VMNames |select Name | Foreach-Object {Write-Verbose $_.Name} | Sort-Object
$VMNumbers = $VMNames |select Name | Foreach-Object {[int]($_.Name -replace '\D').Trim() } | Sort-Object
Write-Verbose "$($VMNumbers.Count) Matching entries found"
# Active Directory
Write-Verbose "Processing Active Directory"
# Issue Query
$searcher = [ADSISearcher]"(&(objectCategory=computer)(name=$($StartOfName)*))"
$searcher.PageSize = 1000
# get next available number in a range of numbers. returns 5 for 1,2,3,4,6,7,9 From AD
$ADNames = $searcher.FindAll() | Foreach-Object {[string]$_.Properties.name} | Sort-Object
$ADNames | Foreach-Object {Write-Verbose $_} | Sort-Object
$ADnumbers = $ADNames | Foreach-Object {[int]($_ -replace '\D').Trim() } | Sort-Object
Write-Verbose "$($ADnumbers.Count) Matching entries found"
# Search DNS
Write-Verbose "Processing DNS"
# Import DNS module
Import-Module dnsShell -Verbose:$false
$DNSNames = get-dnsRecord -server $DNSServer -RecordType A -Zone blah.local | select Name |where {$_.Name -like "$($startOfName)*"}
$DNSNames | Foreach-Object {Write-Verbose $_.Name} | Sort-Object -Unique
$DNSNumbers = $DNSNames | Foreach-Object {[int]($_.Name -replace '\D').Trim() } | Sort-Object -Unique
Write-Verbose "$($DNSNumbers.Count) Matching entries found"
# Search SCCM
Write-Verbose "Processing SCCM 2012"
# Query SCCM2012 Env
$SCCM2012Members = Get-WmiObject -ComputerName $SCCM2012SiteServer -Namespace "ROOT\SMS\site_$SCCM2012SiteCode" -Query "SELECT * FROM SMS_FullCollectionMembership WHERE CollectionID='SMS00001' AND Name LIKE '$($startOfName)%' order by name" | select Name -Unique
$SCCM2012Members |select Name | Foreach-Object {Write-Verbose $_.Name} | Sort-Object
$SCCM2012Numbers = $SCCM2012Members |select Name | Foreach-Object {[int]($_.Name -replace '\D').Trim() } | Sort-Object
Write-Verbose "$($SCCM2012Numbers.Count) Matching entries found"
Write-Verbose "Processing SCCM 2007"
# Query SCCM2007 Env
$SCCM2007Names = Get-WMIObject -ComputerName $SCCM2007SiteServer -Namespace "root\sms\site_$SCCM2007SiteCode" -class "SMS_R_System" -filter "Name LIKE `"$startOfName%`"" |select Name | Sort-Object -Property Name -Unique
$SCCM2007Names |select Name | Foreach-Object {Write-Verbose $_.Name} | Sort-Object
$SCCM2007Numbers = $SCCM2007Names |select Name | Foreach-Object {[int]($_.Name -replace '\D').Trim() } | Sort-Object
Write-Verbose "$($SCCM2007Numbers.Count) Matching entries found"
# Search Production SCOM 2007
Write-Verbose "Processing SCOM 2007"
#Initialize SCOM SnapIn
Add-PSSnapin Microsoft.EnterpriseManagement.OperationsManager.Client -ErrorAction SilentlyContinue -verbose:$false
#Connect to Production SCOM 2007 Env.
$null = New-ManagementGroupConnection -ConnectionString $SCOMServer
#Connect to SCOM Provider
Push-Location 'OperationsManagerMonitoring::'
# Get Agents Matching Name
$SCOM2007Names = Get-ManagementServer |Get-Agent |Where {$_.Name -like "$($startOfName)*"}
$SCOM2007Names | Foreach-Object {Write-Verbose $_.Name} | Sort-Object
$SCOM2007Numbers = $SCOM2007Names | Foreach-Object {[int]($_.Name -replace '\D').Trim() } | Sort-Object
Write-Verbose "$($SCOM2007Numbers.Count) Matching entries found"
# Return to previous location
Pop-Location
# Merge arrays adding a zero so we allways start issuing numbers from the beginning (ie 001)
$list = #(0) + $VMNumbers + $ADnumbers + $DNSNumbers + $SCCM2012Numbers + $SCCM2007Numbers + $SCOM2007Numbers
# Remove Duplicates numbers from the array and sort into numerical order
$list = $list | Sort-Object -Unique
Write-Verbose "Used numbers after sorting: $($list)"
# Determine if next server name is a gap in the sequence in the array
for($i=0; $i -lt $list.length; $i++) {
if( $list[$i+1]-$list[$i] -gt 1) {
# The gap between the current server number and the next element in the array is greater than 1
# So we have an available number we can use.
# TODO: - Add support for consecutive numbers IE build 6 servers with consecutive numbers.
$num = "{0:000}" -f ($list[$i]+1)
break
}
}
# If no gap found in the sequence then use the next number from the sequence in the array
if ($num -eq $null) {
$num = "{0:000}" -f (($list[-1]+1))
}
# Construct new name
$NewComputerName = "{0}{1}" -f $startOfName,$num
# Create DNS Record to 'reserve / mark the name as in use'
Write-Verbose "Creating DNS Reservation"
New-DnsRecord -Name $NewComputerName -IPAddress "127.0.0.1" -Zone blah.local -Type A -Server $DNSServer
write-output $NewComputerName