Get-SpecialFolder: PowerShell function that retrieves special folder (known folders), i.e., folders with special meaning to the OS.

Get-SpecialFolder.ps1

function Get-SpecialFolder {
  <#
  .SYNOPSIS
  Gets special (known) folders.
  
  .DESCRIPTION
  Gets items representing special folders (directories), i.e.,
  folders whose purpose is predefined by the operating system.
  
  In a string context, each such item expands to the full, literal path it 
  represents.

  If no name is given, all special folders known to the current OS
  are listed. Use -All to include those that are special on other platforms.
  
  .PARAMETER Name
  The name(s) of specific special folders to get.
  Note that wildcards are not supported.
  
  .PARAMETER All
  Lists all special folders across all supported platforms, i.e., includes 
  folders that aren't defined for the current OS.
  
  .EXAMPLE
  Get-SpecialFolder UserProfile, Desktop
  
  Gets items representing the current OS' user-profile (home) folder
  and desktop folder.
  
  .EXAMPLE
  Get-SpecialFolder
  
  Lists all special folders defined for the current OS.
  Add -All to see special folders across all supported OSs.
  
  .EXAMPLE
  "The application-data folder is: $(Get-SpecialFolder ApplicationData)"

  Uses the function in an expandable string, showing how the item returned
  expands to its full, literal directory path.

  .NOTES
  Requires version 5 or higher.
  This function is convenient, but not fast.
  #>
  
    [CmdletBinding(PositionalBinding=$False, DefaultParameterSetName='List')]
    param(
      [Parameter(Mandatory, Position=0, ParameterSetName='Name')]
      [ValidateSet('AdminTools', 'ApplicationData', 'CDBurning', 'CommonAdminTools', 'CommonApplicationData', 'CommonDesktopDirectory', 'CommonDocuments', 'CommonMusic', 'CommonOemLinks', 'CommonPictures', 'CommonProgramFiles', 'CommonProgramFilesX86', 'CommonPrograms', 'CommonStartMenu', 'CommonStartup', 'CommonTemplates', 'CommonVideos', 'Cookies', 'Desktop', 'DesktopDirectory', 'Favorites', 'Fonts', 'History', 'InternetCache', 'LocalApplicationData', 'LocalizedResources', 'MyComputer', 'MyDocuments', 'MyMusic', 'MyPictures', 'MyVideos', 'NetworkShortcuts', 'Personal', 'PrinterShortcuts', 'ProgramFiles', 'ProgramFilesX86', 'Programs', 'Recent', 'Resources', 'SendTo', 'StartMenu', 'Startup', 'System', 'SystemX86', 'Templates', 'UserProfile', 'Windows')]
      [string[]] $Name
      ,
      [Parameter(ParameterSetName='List')]
      [switch] $All
    )
  
    [Flags()]
    enum GsfSupportedOs {
      All = 0x7 # !! Sum of all the flags below - BE SURE To UPDATE THIS IF NEW FLAGS ARE ADDED
      Windows = 0x1
      Linux = 0x2
      macOS = 0x4
    }
  
    class GsfSpecialFolder {
      [string] $Name
      [string] $Path
      [GsfSupportedOs] $SupportedOs
      [string] ToString() { return $this.Path }
    }
    
    # Note: The SupportedOs flags were determined by trial and error on each platform, as of .NET Core 2.1
    #       To get all supported names, use:
    #         [enum]::GetNames([System.Environment+SpecialFolder]) | Sort-Object
    $specialFolders = [ordered] @{
      'AdminTools' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'ApplicationData' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'CDBurning' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonAdminTools' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonApplicationData' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'CommonDesktopDirectory' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonDocuments' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonMusic' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonOemLinks' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonPictures' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonProgramFiles' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonProgramFilesX86' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonPrograms' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonStartMenu' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonStartup' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonTemplates' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'CommonVideos' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'Cookies' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'Desktop' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'DesktopDirectory' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'Favorites' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS' }
      'Fonts' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS' }
      'History' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'InternetCache' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS' }
      'LocalApplicationData' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'LocalizedResources' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'MyComputer' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'MyDocuments' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'MyMusic' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'MyPictures' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'MyVideos' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, Linux' }
      'NetworkShortcuts' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'PrinterShortcuts' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'ProgramFiles' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS' }
      'ProgramFilesX86' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'Programs' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'Recent' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'Resources' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'SendTo' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'StartMenu' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'Startup' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'System' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS' }
      'SystemX86' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
      'Templates' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, Linux' }
      'UserProfile' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows, macOS, Linux' }
      'Windows' = [GsfSpecialFolder] @{ Name = ''; Path = $null; SupportedOs = [GsfSupportedOs] 'Windows' }
    }
    
    # Determine the filter to apply to the list of all special folders.
    if ($PSCmdlet.ParameterSetName -eq 'List') {
      $thisOs = if ($IsMacOS) { [GsfSupportedOs]::macOS } elseif ($IsLinux) { [GsfSupportedOs]::Linux } else { [GsfSupportedOs]::Windows }
      $sbFilter = if ($All) { { $True } } else { { $_.Value.SupportedOs -band $thisOS } }
    } else {
      $sbFilter = { $_.Key -in $Name }
    }
  
    # Get the filtered list and flesh out the output objects.
    $specialFolders.GetEnumerator() | Where-Object $sbFilter | ForEach-Object { 
      $_.Value.Name = $_.Key
      $_.Value.Path = [Environment]::GetFolderPath($_.Key)
      $_.Value
    }
  
}

# If this script is invoked directly - as opposed to being dot-sourced in order
# to define the embedded function for later use - invoke the embedded function,
# relaying any arguments passed.
if (-not ($MyInvocation.InvocationName -eq '.' -or $MyInvocation.Line -eq '')) {
  Get-SpecialFolder @Args
}