RUNDLL and RUNDLL32

RUNDLL and RUNDLL32 are two utilities supplied with Windows 95 and later.
They can call DLL functions from the command line, allowing us to create extremely powerfull batch files.

Some examples:

  1. Start Control Panel applets (2)

    General syntax:

    RUNDLL32 SHELL32.DLL,Control_RunDLL filename.CPL,@n,t

    where:

    filename.CPL
    is the name of one of Control Panel's *.CPL files,
    n
    is the zero based number of the applet within the *.CPL file, and
    t
    is the number of the tab for multi paged applets

    Examples:

    Date/time applet, Time Zone tab:
    RUNDLL32 SHELL32.DLL,Control_RunDLL TIMEDATE.CPL,@0,1
    Desktop applet, Screensaver tab:
    RUNDLL32 SHELL32.DLL,Control_RunDLL DESK.CPL,@0,1
    Network applet, Protocols tab:
    RUNDLL32 SHELL32.DLL,Control_RunDLL NCPA.CPL,@0,2
    Network applet, Adapters tab:
    RUNDLL32 SHELL32.DLL,Control_RunDLL NCPA.CPL,@0,3
    System applet, Environment tab:
    RUNDLL32 SHELL32.DLL,Control_RunDLL SYSDM.CPL,@0,2

    An alternative approach is using CONTROL.EXE.
    However, if you want to make your batch file wait for the Control Panel applet to be closed, you'll have to use the RUNDLL32 command with START /WAIT

    General syntax:

    CONTROL.EXE filename.CPL,@n,t

    where:

    filename.CPL
    is the name of one of Control Panel's *.CPL files,
    n
    is the zero based number of the applet within the *.CPL file, and
    t
    is the number of the tab for multi paged applets

    Examples:

    Date/time applet, Time Zone tab:
    CONTROL.EXE TIMEDATE.CPL,@0,1
    Desktop applet, Screensaver tab:
    CONTROL.EXE DESK.CPL,@0,1
    or alternatively, in Windows 2000 & XP:
    CONTROL.EXE DESK.CPL ,@ScreenSaver
    Note the space between the *.CPL file name and the comma.
    This seems to work for DESK.CPL only.
    Use the description on the tab, remove any spaces.

    Credits: Neil J. Rubenking, in one of his articles in PC Magazine.
    Tip: Leslie Katz

  2. Open Install new modem wizard:

    RUNDLL32 modemui.dll,InvokeControlPanel

    Credits: Jeffrey W. Horning (posted on JSI FAQ)

  3. Start "Add New Hardware" Wizard (Windows 95):

    RUNDLL SYSDM.CPL,InstallDevice_Rundll

    Credits: Faris Mlaeb

  4. Open the "Unplug or Eject Hardware" wizard (Windows 2000 or later, or Windows 98 SE with hotplug.dll installed):

    RUNDLL32 SHELL32.DLL,Control_RunDLL hotplug.dll

    Credits: Chris S./Dx21.com

  5. Open Device manager:

    RUNDLL32 devmgr.dll DeviceManager_Execute

    Credits: Jeffrey W. Horning (posted on JSI FAQ)

  6. Install a screensaver (copy the *.SCR file to the Windows directory first) (2):

    RUNDLL32 DESK.CPL,InstallScreenSaver C:\WINNT\SYSTEM32\Default.scr

    (To invoke the screensaver use:

    C:\WINNT\SYSTEM32\Default.scr /S

    Tip by "UnhappyEggWhisk" on forums.somethingawful.com)

    The directory shown is for Windows NT 4/2000, modify for Windows 9x/XP

  7. Lock the screen (Windows 2000):

    RUNDLL32 USER32.DLL,LockWorkStation

    Credits: Steven Clements (posted on alt.msdos.batch.nt)

  8. Redraw the screen (Windows 95):

    RUNDLL USER,repaintscreen

    Credits: Faris Mlaeb

  9. Rearrange the windows on the screen (Windows 95):

    Cascade:
    RUNDLL32 USER,cascadechildwindows
    Tile:
    RUNDLL32 USER,tilechildwindows

    Credits: Faris Mlaeb

  10. Change screen resolution (Windows 9x with PowerToys' QuickRes installed):

    RUNDLL DESKCP16.DLL,QUICKRES_RUNDLLENTRY hresxvresxbpp

    Where hres is the horizontal resolution in pixels, vres is the vertical resolution in pixels, and bpp is the number of bits per pixel.
    The following example will set the screen resolution to 800 x 600 at 256 colors (28 colors = 8 bits per pixel)

    RUNDLL DESKCP16.DLL,QUICKRES_RUNDLLENTRY 800x600x8

    Credits: William Allen (posted on alt.msdos.batch)

  11. Disable mouse and/or keyboard (Windows 9*/ME):

    RUNDLL KEYBOARD,DISABLE
    RUNDLL MOUSE,DISABLE

    There is an ENABLE function too, but I haven't found the right syntax yet. Without any further parameters it only halts the system without warning (Windows 95). You will probably need the other RUNDLL commands to do a "clean" reboot.

    Credits: Koro das Master

  12. Halt system:

    RUNDLL MOUSE,ENABLE

    Credits: Faris Mlaeb

  13. Start "Add New Printer" wizard:

    RUNDLL32 SHELL32.DLL,SHHelpShortcuts_RunDLL AddPrinter

  14. Open "Connect to Printer" dialog:

    RUNDLL32 WINSPOOL.DRV,ConnectToPrinterDlg

    This commands opens the "Connect to Printer" dialog, as you might have guessed. I don't see any useful application yet, but maybe you do.

  15. Open the Printers folder:

    RUNDLL32 SHELL32.DLL,Control_RunDLL MAIN.CPL @2

    or for Windows 2000:

    RUNDLL32 SHELL32.DLL,SHHelpShortcuts_RunDLL PrintersFolder

    Credits: Pascal Rebsamen

    Note: To create a shortcut in the Start Menu to open the Printers folder, create a directory using one of the following commands.

    Windows 9x (without roaming profiles):
    MD "%windir%\Start Menu\Programs\Printers.{2227A280-3AEA-1069-A2DE-08002B30309D}"
    Windows NT 4/2000:
    MD "%USERPROFILE%\Start Menu\Programs\Printers.{2227A280-3AEA-1069-A2DE-08002B30309D}"

  16. Print a test page (Windows 95 and later; unfortunately this command does not always work):

    RUNDLL32.EXE SHELL32.DLL,SHHelpShortcuts_RunDLL PrintTestPage

    Or for Windows 9x (source: Daniel U. Thibault):

    RUNDLL32.EXE MSPrint2.DLL,RUNDLL_PrintTestPage

  17. View or change printer settings (Windows 2000):

    RUNDLL32 PRINTUI.DLL,PrintUIEntry /?

    This will display an extensive list of available functions and many examples.
    View this same list in HTML.

  18. Add a TCP/IP printer port:

    RUNDLL32 tcpmonui.dll,LocalAddPortUI

    Credits: Jeffrey W. Horning (posted on JSI FAQ)

  19. Open the dialog box for editing the Favorites in Internet Explorer:

    RUNDLL32.EXE shdocvw.dll,DoOrganizeFavDlg

    Credits: "pradeep" (posted on Go4Expert Forum)

  20. Start GUI mode disk format:

    RUNDLL32 SHELL32.DLL,SHFormatDrive

  21. Start GUI mode diskcopy:

    RUNDLL32 DISKCOPY.DLL,DiskCopyRunDll

    Credits: Media Chance

  22. "Map Network Drive" dialog (Windows 95):

    RUNDLL32 USER,wnetconnectdialog

    and for Windows XP:

    RUNDLL32 SHELL32.DLL,SHHelpShortcuts_RunDLL Connect

    Credits: Faris Mlaeb (Windows 95) and Ian Freeman (Windows XP)

  23. Manage shares:

    RUNDLL32 ntlanui.dll,ShareManage - Shares

    Credits: Jeffrey W. Horning (posted on JSI FAQ)

  24. Create a new share:

    RUNDLL32 ntlanui.dll,ShareCreate

    Credits: Jeffrey W. Horning (posted on JSI FAQ)

  25. Open the Network ID wizard:

    RUNDLL32 netplwiz.dll,NetAccWizRunDll

    Credits: Jeffrey W. Horning (posted on JSI FAQ)

  26. Open the Add network place wizard:

    RUNDLL32 netplwiz.dll,AddNetPlaceRunDll

    Credits: Jeffrey W. Horning (posted on JSI FAQ)

  27. Logoff Windows (1)

    Logoff Windows 98:
    RUNDLL SHELL32.DLL,SHExitWindowsEx
    Logoff Windows 98 and run Explorer after relogon:
    RUNDLL SHELL32.DLL,SHExitWindowsEx 4
    Logoff Windows NT 4:
    RUNDLL32 USER32.DLL,ExitWindowsEx
    RUNDLL32 USER32.DLL,ExitWindowsEx
    This is not a mistake, the command usualy must be called twice before anything happens.

  28. Reboot (1)

    Windows 95 (not reliable, sometimes only shutdown):
    RUNDLL USER.EXE,ExitWindowsExec
    Windows 98:
    RUNDLL SHELL32.DLL,SHExitWindowsEx 2
    Windows NT 4:
    @ECHO OFF
    PUSHD "%temp%"
    ECHO [Version] > {out}.inf
    ECHO signature=$chicago$ >> {out}.inf
    ECHO [defaultinstall] >> {out}.inf
    RUNDLL32 SETUPAPI,InstallHinfSection DefaultInstall 1 {out}.inf
    DEL {out}.inf
    POPD
    (original batch file by Walter Zackery, adapted for readability)

  29. Shutdown (1)

    Windows 95:
    RUNDLL USER.EXE,ExitWindows
    Windows 98:
    RUNDLL SHELL32.DLL,SHExitWindowsEx 1
    or:
    RUNDLL32 KRNL386.EXE,exitkernel
    (will also power down ATX boards)

  30. Activate suspend mode (1) (Windows 2000/XP):

    RUNDLL32 PowrProf.dll, SetSuspendState

    Credits: TechRepublic's Windows XP Newsletter & Graham Smith.

  31. Show Windows 9*'s "System setting changed, do you want to reboot now?" dialog (1):

    RUNDLL SHELL.DLL,RestartDialog

  32. Display NT's "About" dialog, showing version, servicepack, registered owner and amount of physical memory:

    RUNDLL32 SHELL32.DLL,ShellAboutW

  33. Open a file with Windows' "Open as" dialog:

    RUNDLL32 SHELL32.DLL,OpenAs_RunDLL filename

  34. Open a .ZIP file in Explorer (XP):

    RUNDLL32.EXE ZIPFLDR.DLL,RouteTheCall zipfile.ZIP

    Unfortunately, there seems to be no (native) command to copy files into the .ZIP file

  35. Swap your mouse to left handed use (tip from "Speedy Gonzales"):

    Windows 95:
    RUNDLL USER.EXE,SwapMouseButton
    Windows NT:
    RUNDLL32 USER32.DLL,SwapMouseButton

    I know of no command yet to undo this, but the following will get you close:

    CONTROL MAIN.CPL

    or:

    RUNDLL32 SHELL32.DLL,Control_RunDLL MAIN.CPL,@0,1

  36. Start "DialUp Connection" Wizard (Windows 95):

    RUNDLL RNAUI.DLL,RnaWizard

    Credits: Faris Mlaeb

  37. Start DialUp Network:

    START RUNDLL32 RNAUI.DLL,RnaDial exact name of dialer entry
    TRACERT -h 1 -w 1

    The RUNDLL command starts DUN, the TRACERT command is supposed to actually start the dialing process, assuming automatic dialing is enabled.
    Since I do not have access to any PC with DUN installed, I could not test the TRACERT command's effect.

    Credits for these commands: Michael J. Gregg and Tom Lavedas

    Use the RASPHONE command in Windows NT, which can also hang up the connection

    Credits: Simon Sheppard.

  38. Open the Fonts folder:

    RUNDLL32 SHELL32.DLL,SHHelpShortcuts_RunDLL FontsFolder

    Credits: Media Chance

  39. TechRepublic's Windows XP e-Newsletter for August 5, 2004, showed a nice example of using RUNDLL32 to open an Active Directory Search window:

    RUNDLL32 dsquery,OpenQueryWindow

    This allows you to search Active Directory for users or computers, though only a limited part of the properties is accessible.

  40. Activate registry changes in HKEY_CURRENT_USER without logging off (Windows 2000 and later):

    RUNDLL32.EXE USER32.DLL,UpdatePerUserSystemParameters ,1 ,True

    Credits: Pete Smith.

  41. Remove Messenger (Windows XP):

    RUNDLL32 advpack.dll,LaunchINFSection %windir%\INF\msmsgs.inf,BLC.Remove

    Credits: Pascal Rebsamen (posted on WinBoard)

  42. Repair IE 6 (Windows XP):

    RUNDLL32 setupapi,InstallHinfSection DefaultInstall 132 %windir%infie.inf

    Credits: Pascal Rebsamen (posted on WinBoard)

 

Notes: (1) See my Shutdown page for more information and examples on reboot and shutdown command lines.
  (2) By associating *.CPL files with the command
RUNDLL32 SHELL32.DLL,Control_RunDLL %1,@0
and *.SCR files with
RUNDLL32 DESK.CPL,InstallScreenSaver %1
you can open and/or install them by doubleclicking on their icons.

 

Install a screensaver

The following batch file installs a screensaver if one is specified, and opens the Control Panel applet at the right tab to enable adjustment of its settings (tested in NT only):

@ECHO OFF
IF "%1"=="" GOTO Interactive
IF NOT EXIST %SystemRoot%.\System32\%~nx1 GOTO Interactive

RUNDLL32 DESK.CPL,InstallScreenSaver %~f1
GOTO End

:Interactive
RUNDLL32 SHELL32.DLL,Control_RunDLL DESK.CPL,@0,1

:End
Click to view source Click to download the ZIPped source

 

 

I am interested to hear about other possible uses for RUNDLL32.
Please send me your tips or comments by e-mail:                                                                                                                                                                                                                                                               
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More to explore

 

An extensive list of RUNDLL commands with good search capabilities can be found at Dx21's RunDLL32 section.

For programmers, there is more information on Microsoft's Windows 95 Rundll and Rundll32 Interface page.
On Robert Vivrette's The Unofficial Newsletter of Delphi Users you can find an article about RUNDLL by Wendell Jones (brought to my attention by William Brooks in response to my request for tips; thanks).

Peter A. Bromberg's Short RunDll32 Primer for Developers.

How INF files work by Mike Williams.

At The Visual Basic Developers Resource Centre a list of Control Panel Functions for Windows 9x/NT through RUNDLL can be found (a tip from my former collegue Adriaan Westra; thanks).

An extensive list of Control Panel related and other RUNDLL commands can be found at Media Chance's RUNDLL FAQ page.

Jeffrey W. Horning provided a list of Undocuments paths to Windows 2000 tools (thanks for Viju Chellamuthu, who mailed me the link).