Get-TooLongFileName

function Get-TooLongFileName
    {
    #region Comment Based Help [CBH]
    #    trailing blank line required by CBH

    <#
    .SYNOPSIS
        Gets the names of files that are longer than specified.
    .DESCRIPTION
        Uses Robocopy [with /L to avoid any changes] to get file names that are longer than specified.
        Scans the entire folder tree starting at the $Source location.
        Returns [a] $Null [no files]
                [b] a string [one file]
                [c] an array of strings [two or more files]
    .EXAMPLE
        Get-LongFileName -Source C:\temp

        Scans the folder tree starting at C:\temp.
        Returns any file names that are longer than the default of 250 characters.
    .EXAMPLE
        Get-LongFileName -Source C:\temp -MaxFQFN_Length 90

        Scans the folder tree starting at C:\temp.
        Returns any file names that are longer than 90 characters.
    .NOTES
        Version = 2017-02-24_-_21-40

        Robocopy Documentation
        - https://technet.microsoft.com/en-us/library/cc733145
    #>

    #    leading blank line required by CBH
    #endregion

    #region Parameters
    [CmdletBinding ()]
    [OutputType ([string[]])]

    Param (
        # Directory to start scanning the folder tree.
        [Parameter (
            Mandatory,
            Position = 0,
            HelpMessage = "Please enter the directory to start scanning the folder tree."
            )]
            [ValidateScript (
                {
                if (Test-Path $_)
                    {
                    $True
                    }
                    else
                    {
                    throw "`n`nPath >> $_ << not found.`n"
                    }
                })]
            [string]
            $Source,

        # Longest allowed Fully Qualified File Name length.
        [Parameter (
            Position = 1
            )]
            [ValidateRange (0, 250)]
            [int]
            $MaxFQFN_Length = 250
        )
    #endregion

    # Giving robocopy a REAL destination here makes it include it as a source.
    #    Leaving it off makes it complain about not having a destination.
    #    That disagrees with the docs. I have no idea why.
    #    Using NULL [a string, not the variable $Null] works.
    #        Thanks to /u/Martin9700 for the idea.
    $Destination = 'NULL'

    #region Robocopy parameter list
    <#
         source :: Source Directory (drive:\path or \\server\share\path).
    destination :: Destination Dir  (drive:\path or \\server\share\path).
             /S :: copy Subdirectories, but not empty ones.
            /XJ :: eXclude Junction points. (normally included by default).
           /R:n :: number of Retries on failed copies: default 1 million.
           /W:n :: Wait time between retries: default is 30 seconds.
             /L :: List only - don't copy, timestamp or delete any files.
            /FP :: include Full Pathname of files in the output.
            /NS :: No Size - don't log file sizes.
            /NC :: No Class - don't log file classes.
           /NDL :: No Directory List - don't log directory names.
            /NP :: No Progress - don't display percentage copied.
           /NJH :: No Job Header.
           /NJS :: No Job Summary.
    #>
    #endregion

    $RC_Params = ($Source, $Destination) +
        "/S /XJ /R:0 /W:0 /L /FP /NS /NC /NDL /NP /NJH /NJS".Split(' ')

    $RC_FileList = robocopy $RC_Params |
        ForEach-Object {$_.Trim()} |
        Where-Object {$_.Length -gt $MaxFQFN_Length} |
        Sort-Object -Property Length

    return $RC_FileList

    } # end of function



Get-TooLongFileName -Source $env:TEMP -MaxFQFN_Length 50