Powershell: Find numbers in name folders

Question

I have in a directory that contains the following folders:

000000000000000000, 0001251557a1485767, 0144dshbc, 014758, 111147857484752169 and 123456789012345678z

And I use this code to find folders based on their name:

Get-ChildItem | Where-Object {$_.Name -notmatch "[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]"}

I would like this code to return only the names of folders whose names do not contain exactly 18 numeric characters. So, the result should be something like:

0144dshbc, 014758, 0001251557a1485767 and 123456789012345678z

But when I run these command, I will get these folders:

0001251557a1485767, 0144dshbc and 014758

My Question: How do I also find folder " 123456789012345678z ", which has 18 numbers in the name, but has a letter at the end.

My goal is to find all folders that don't have 18 numeric characters. Thanks.

Answer 1

This code will find files that do not have exactly 18 all numeric characters in the name. The verbose logging will show you how each value is rated. The non-matching values are returned on the pipeline.

$VerbosePreference = 'continue'

$list = Get-ChildItem | Select-Object -ExpandProperty Name
foreach ($item in $list)
{

    if($item.Length -eq 18 -and $item -match '^[0-9]+$' )
    {
        Write-verbose 'is both 18 chars and numeric'
        Write-verbose "- $item, length: $($item.Length)"
    }
    else
    {
        Write-verbose 'is not 18 chars and numeric'
        Write-verbose "- $item, length: $($item.Length)"
        Write-Output $item
    }
}

All of the important logic is in the IF() statement. Checking for length understandable. The match operator looks for a string that begins with (indicated by the ^) one or more (indicated by the +) numbers (the [0-9]) and immediately hits the end of the string (the $).