Get-ChildFilePath.ps1

function Get-ChildFilePath {
<#
.SYNOPSIS
    Get-ChildFilePath returns a list of file paths of children recursively.
    This supports long file name (>256 characters).
.DESCRIPTION
    Get-ChildFilePath returns an array of string of full path,
    in contrast to Get-ChildItem, which returns an array of object.
    Get-ChildFilePath is twice as Get-ChildItem.
.PARAMETER Path
    Parent directory path
.INPUTS
    Get-ChildFilePath supports pipeline input to $Path.
.OUTPUTS
    a list of file paths ([String[]]).
.EXAMPLE 
    PS C:\Sample> Get-ChildFilePath "C:\"
#>
  [CmdletBinding()]
  [OutputType([String[]])]
  param (
    [Parameter(Mandatory,ValueFromPipeline)]
    [string]$Path
  )

  BEGIN {
    $notexist = 'C:\DOESNOTEXIST';
    while (Test-Path $notexist){
      $notexist += Get-Random $(48..57+97..122) | % {[char]$_}
    }
  }

  PROCESS {
    if( Test-Path $Path ){
      $list = robocopy.exe $Path $notexist /L /E /B /NP /FP /NS /NC /NJH /NJS /NDL |
        ForEach-Object { $_.Trim() } | Where-Object { $_.Length -gt 0 }
      @($list)
    } else {
      @()
    }
  }
}