Getting any special folder path in Powershell using folder GUID

Question

I want to use a PowerShell script to automate tasks related to the user when the user logs in.

Sometimes a user will have moved his Documents folder from the default location. How can I determine the location of the user's Documents folder in PowerShell with a method that will work for all special folders?

I tried to use SHGetKnownFolderPath calls from PowerShell based on Lee Holmes work

As pinvoke website C# sample doesn't use StringBuilder, I assumed it was not required and stripped builder + "-Using" references

param($KNOWNFOLDERID)

$Pinvoke = @’
[DllImport("shell32.dll")]
public static extern int SHGetKnownFolderPath(
     [MarshalAs(UnmanagedType.LPStruct)] Guid rfid,
     uint dwFlags,
     IntPtr hToken,
     out String pszPath  // API uses CoTaskMemAlloc
     );
‘@

$type = Add-Type -MemberDefinition $Pinvoke  
    -Name Win32Utils -Namespace SHGetKnownFolderPath  
    -PassThru

$type::SHGetKnownFolderPath($KNOWNFOLDERID) 

I also tried to use New-PInvoke from here with "shell32.dll" as lib value and

int SHGetKnownFolderPath(     [MarshalAs(UnmanagedType.LPStruct)] Guid rfid,     uint dwFlags,     IntPtr hToken,     out String pszPath  )

as signature value, then using from powershell

SHGetKnownFolderPath FDD39AD0-238F-46AF-ADB4-6C85480369C7 0 0 [ref]$path

I ends with this error

Argument: '4' should be a System.Management.Automation.PSReference. Use [ref].
At line:1 char:56
+ New-Item Function:Global:SHGetKnownFolderPath -Value { [Microsoft.PowerShell.Com ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodException
    + FullyQualifiedErrorId : NonRefArgumentToRefParameterMsg

I don't understand where I got wrong on both trials.

SOLUTION:
Windows7Library binary found by Kayasax on codeplex works for lazy people like me, or David Heffernan 's scriptlet that allow more customization, but may need some handwork if you use custom special folders, but more customizable, both answers are valid !

Answer 1

It's easier to wrap up the low-level p/invoke in C# code than it is to attempt to call it directly from PowerShell. Here I've taken the pinvoke.net declarations and wrapped them up in a simple method that accepts a known folder GUID and returns the path.

Add-Type @"

    using System;
    using System.Runtime.InteropServices;

    public static class KnownFolder
    {
        public static readonly Guid AddNewPrograms = new Guid( "de61d971-5ebc-4f02-a3a9-6c82895e5c04" );
        public static readonly Guid AdminTools = new Guid( "724EF170-A42D-4FEF-9F26-B60E846FBA4F" );
        public static readonly Guid AppUpdates = new Guid( "a305ce99-f527-492b-8b1a-7e76fa98d6e4" );
        public static readonly Guid CDBurning = new Guid( "9E52AB10-F80D-49DF-ACB8-4330F5687855" );
        public static readonly Guid ChangeRemovePrograms = new Guid( "df7266ac-9274-4867-8d55-3bd661de872d" );
        public static readonly Guid CommonAdminTools = new Guid( "D0384E7D-BAC3-4797-8F14-CBA229B392B5" );
        public static readonly Guid CommonOEMLinks = new Guid( "C1BAE2D0-10DF-4334-BEDD-7AA20B227A9D" );
        public static readonly Guid CommonPrograms = new Guid( "0139D44E-6AFE-49F2-8690-3DAFCAE6FFB8" );
        public static readonly Guid CommonStartMenu = new Guid( "A4115719-D62E-491D-AA7C-E74B8BE3B067" );
        public static readonly Guid CommonStartup = new Guid( "82A5EA35-D9CD-47C5-9629-E15D2F714E6E" );
        public static readonly Guid CommonTemplates = new Guid( "B94237E7-57AC-4347-9151-B08C6C32D1F7" );
        public static readonly Guid ComputerFolder = new Guid( "0AC0837C-BBF8-452A-850D-79D08E667CA7" );
        public static readonly Guid ConflictFolder = new Guid( "4bfefb45-347d-4006-a5be-ac0cb0567192" );
        public static readonly Guid ConnectionsFolder = new Guid( "6F0CD92B-2E97-45D1-88FF-B0D186B8DEDD" );
        public static readonly Guid Contacts = new Guid( "56784854-C6CB-462b-8169-88E350ACB882" );
        public static readonly Guid ControlPanelFolder = new Guid( "82A74AEB-AEB4-465C-A014-D097EE346D63" );
        public static readonly Guid Cookies = new Guid( "2B0F765D-C0E9-4171-908E-08A611B84FF6" );
        public static readonly Guid Desktop = new Guid( "B4BFCC3A-DB2C-424C-B029-7FE99A87C641" );
        public static readonly Guid Documents = new Guid( "FDD39AD0-238F-46AF-ADB4-6C85480369C7" );
        public static readonly Guid Downloads = new Guid( "374DE290-123F-4565-9164-39C4925E467B" );
        public static readonly Guid Favorites = new Guid( "1777F761-68AD-4D8A-87BD-30B759FA33DD" );
        public static readonly Guid Fonts = new Guid( "FD228CB7-AE11-4AE3-864C-16F3910AB8FE" );
        public static readonly Guid Games = new Guid( "CAC52C1A-B53D-4edc-92D7-6B2E8AC19434" );
        public static readonly Guid GameTasks = new Guid( "054FAE61-4DD8-4787-80B6-090220C4B700" );
        public static readonly Guid History = new Guid( "D9DC8A3B-B784-432E-A781-5A1130A75963" );
        public static readonly Guid InternetCache = new Guid( "352481E8-33BE-4251-BA85-6007CAEDCF9D" );
        public static readonly Guid InternetFolder = new Guid( "4D9F7874-4E0C-4904-967B-40B0D20C3E4B" );
        public static readonly Guid Links = new Guid( "bfb9d5e0-c6a9-404c-b2b2-ae6db6af4968" );
        public static readonly Guid LocalAppData = new Guid( "F1B32785-6FBA-4FCF-9D55-7B8E7F157091" );
        public static readonly Guid LocalAppDataLow = new Guid( "A520A1A4-1780-4FF6-BD18-167343C5AF16" );
        public static readonly Guid LocalizedResourcesDir = new Guid( "2A00375E-224C-49DE-B8D1-440DF7EF3DDC" );
        public static readonly Guid Music = new Guid( "4BD8D571-6D19-48D3-BE97-422220080E43" );
        public static readonly Guid NetHood = new Guid( "C5ABBF53-E17F-4121-8900-86626FC2C973" );
        public static readonly Guid NetworkFolder = new Guid( "D20BEEC4-5CA8-4905-AE3B-BF251EA09B53" );
        public static readonly Guid OriginalImages = new Guid( "2C36C0AA-5812-4b87-BFD0-4CD0DFB19B39" );
        public static readonly Guid PhotoAlbums = new Guid( "69D2CF90-FC33-4FB7-9A0C-EBB0F0FCB43C" );
        public static readonly Guid Pictures = new Guid( "33E28130-4E1E-4676-835A-98395C3BC3BB" );
        public static readonly Guid Playlists = new Guid( "DE92C1C7-837F-4F69-A3BB-86E631204A23" );
        public static readonly Guid PrintersFolder = new Guid( "76FC4E2D-D6AD-4519-A663-37BD56068185" );
        public static readonly Guid PrintHood = new Guid( "9274BD8D-CFD1-41C3-B35E-B13F55A758F4" );
        public static readonly Guid Profile = new Guid( "5E6C858F-0E22-4760-9AFE-EA3317B67173" );
        public static readonly Guid ProgramData = new Guid( "62AB5D82-FDC1-4DC3-A9DD-070D1D495D97" );
        public static readonly Guid ProgramFiles = new Guid( "905e63b6-c1bf-494e-b29c-65b732d3d21a" );
        public static readonly Guid ProgramFilesX64 = new Guid( "6D809377-6AF0-444b-8957-A3773F02200E" );
        public static readonly Guid ProgramFilesX86 = new Guid( "7C5A40EF-A0FB-4BFC-874A-C0F2E0B9FA8E" );
        public static readonly Guid ProgramFilesCommon = new Guid( "F7F1ED05-9F6D-47A2-AAAE-29D317C6F066" );
        public static readonly Guid ProgramFilesCommonX64 = new Guid( "6365D5A7-0F0D-45E5-87F6-0DA56B6A4F7D" );
        public static readonly Guid ProgramFilesCommonX86 = new Guid( "DE974D24-D9C6-4D3E-BF91-F4455120B917" );
        public static readonly Guid Programs = new Guid( "A77F5D77-2E2B-44C3-A6A2-ABA601054A51" );
        public static readonly Guid Public = new Guid( "DFDF76A2-C82A-4D63-906A-5644AC457385" );
        public static readonly Guid PublicDesktop = new Guid( "C4AA340D-F20F-4863-AFEF-F87EF2E6BA25" );
        public static readonly Guid PublicDocuments = new Guid( "ED4824AF-DCE4-45A8-81E2-FC7965083634" );
        public static readonly Guid PublicDownloads = new Guid( "3D644C9B-1FB8-4f30-9B45-F670235F79C0" );
        public static readonly Guid PublicGameTasks = new Guid( "DEBF2536-E1A8-4c59-B6A2-414586476AEA" );
        public static readonly Guid PublicMusic = new Guid( "3214FAB5-9757-4298-BB61-92A9DEAA44FF" );
        public static readonly Guid PublicPictures = new Guid( "B6EBFB86-6907-413C-9AF7-4FC2ABF07CC5" );
        public static readonly Guid PublicVideos = new Guid( "2400183A-6185-49FB-A2D8-4A392A602BA3" );
        public static readonly Guid QuickLaunch = new Guid( "52a4f021-7b75-48a9-9f6b-4b87a210bc8f" );
        public static readonly Guid Recent = new Guid( "AE50C081-EBD2-438A-8655-8A092E34987A" );
        public static readonly Guid RecycleBinFolder = new Guid( "B7534046-3ECB-4C18-BE4E-64CD4CB7D6AC" );
        public static readonly Guid ResourceDir = new Guid( "8AD10C31-2ADB-4296-A8F7-E4701232C972" );
        public static readonly Guid RoamingAppData = new Guid( "3EB685DB-65F9-4CF6-A03A-E3EF65729F3D" );
        public static readonly Guid SampleMusic = new Guid( "B250C668-F57D-4EE1-A63C-290EE7D1AA1F" );
        public static readonly Guid SamplePictures = new Guid( "C4900540-2379-4C75-844B-64E6FAF8716B" );
        public static readonly Guid SamplePlaylists = new Guid( "15CA69B3-30EE-49C1-ACE1-6B5EC372AFB5" );
        public static readonly Guid SampleVideos = new Guid( "859EAD94-2E85-48AD-A71A-0969CB56A6CD" );
        public static readonly Guid SavedGames = new Guid( "4C5C32FF-BB9D-43b0-B5B4-2D72E54EAAA4" );
        public static readonly Guid SavedSearches = new Guid( "7d1d3a04-debb-4115-95cf-2f29da2920da" );
        public static readonly Guid SEARCH_CSC = new Guid( "ee32e446-31ca-4aba-814f-a5ebd2fd6d5e" );
        public static readonly Guid SEARCH_MAPI = new Guid( "98ec0e18-2098-4d44-8644-66979315a281" );
        public static readonly Guid SearchHome = new Guid( "190337d1-b8ca-4121-a639-6d472d16972a" );
        public static readonly Guid SendTo = new Guid( "8983036C-27C0-404B-8F08-102D10DCFD74" );
        public static readonly Guid SidebarDefaultParts = new Guid( "7B396E54-9EC5-4300-BE0A-2482EBAE1A26" );
        public static readonly Guid SidebarParts = new Guid( "A75D362E-50FC-4fb7-AC2C-A8BEAA314493" );
        public static readonly Guid StartMenu = new Guid( "625B53C3-AB48-4EC1-BA1F-A1EF4146FC19" );
        public static readonly Guid Startup = new Guid( "B97D20BB-F46A-4C97-BA10-5E3608430854" );
        public static readonly Guid SyncManagerFolder = new Guid( "43668BF8-C14E-49B2-97C9-747784D784B7" );
        public static readonly Guid SyncResultsFolder = new Guid( "289a9a43-be44-4057-a41b-587a76d7e7f9" );
        public static readonly Guid SyncSetupFolder = new Guid( "0F214138-B1D3-4a90-BBA9-27CBC0C5389A" );
        public static readonly Guid System = new Guid( "1AC14E77-02E7-4E5D-B744-2EB1AE5198B7" );
        public static readonly Guid SystemX86 = new Guid( "D65231B0-B2F1-4857-A4CE-A8E7C6EA7D27" );
        public static readonly Guid Templates = new Guid( "A63293E8-664E-48DB-A079-DF759E0509F7" );
        public static readonly Guid TreeProperties = new Guid( "5b3749ad-b49f-49c1-83eb-15370fbd4882" );
        public static readonly Guid UserProfiles = new Guid( "0762D272-C50A-4BB0-A382-697DCD729B80" );
        public static readonly Guid UsersFiles = new Guid( "f3ce0f7c-4901-4acc-8648-d5d44b04ef8f" );
        public static readonly Guid Videos = new Guid( "18989B1D-99B5-455B-841C-AB7C74E4DDFC" );
        public static readonly Guid Windows = new Guid( "F38BF404-1D43-42F2-9305-67DE0B28FC23" );
    }

    public class shell32
    {
        [DllImport("shell32.dll")]
        private static extern int SHGetKnownFolderPath(
             [MarshalAs(UnmanagedType.LPStruct)] 
             Guid rfid,
             uint dwFlags,
             IntPtr hToken,
             out IntPtr pszPath
         );

         public static string GetKnownFolderPath(Guid rfid)
         {
            IntPtr pszPath;
            if (SHGetKnownFolderPath(rfid, 0, IntPtr.Zero, out pszPath) != 0)
                return ""; // add whatever error handling you fancy
            string path = Marshal.PtrToStringUni(pszPath);
            Marshal.FreeCoTaskMem(pszPath);
            return path;
         }
    }

"@

Example usage

PS C:\Users\username\Desktop> .\SHGetKnownFolderPath.ps1
PS C:\Users\username\Desktop> [shell32]::GetKnownFolderPath([KnownFolder]::Documents)
C:\Users\username\Documents
PS C:\Users\username\Desktop> [shell32]::GetKnownFolderPath([KnownFolder]::Downloads)
C:\Users\username\Downloads
PS C:\Users\username\Desktop> [shell32]::GetKnownFolderPath([KnownFolder]::InternetCache)
C:\Users\username\AppData\Local\Microsoft\Windows\Temporary Internet Files

I know pretty much nothing about PowerShell, so I am confident that an experienced user will be able to wrap this up in a more idomatic PowerShell manner. However, I'm sure that the basic concept of handling the somewhat gnarly p/invoke inside the C# code, and presenting a higher-level interface to the PowerShell consumer is the right way to tackle this problem.

Answer 2

you can list all the special folders with this command :

[enum]::GetNames([System.Environment+SpecialFolder])  

If you want to get a physical path use this :

[environment]::getfolderpath("mydocuments")