How do I know if a DLL is registered?

Solution 1:

I've found this link: How can I tell whether a DLL has been registered?:

Given that DLL registration can encompass arbitrary operations, there is no general-purpose way of determining whether registration has taken place for an arbitrary DLL.

To determine whether a DLL has been registered, you need to bring in domain-specific knowledge. If you know that a DLL registers a COM object with a particular CLSID, you can check whether that CLSID is indeed registered.

OK, it is impossible, but DLLs usually register themselves creating an entry in the register. A workaround is to:

  1. First you have to discover the COM GUID of the DLL. If you have one machine where it is already registered, you can:
    1. Open regedit and search for your DLL filename
    2. If it is registered, you will find filename under a key that is under the TypeLib. The key will look like: {9F3DBFEE-FD77-4774-868B-65F75E7DB7C2}
  2. Now that you know the DLL GUID, you can search for it with this command in a DOS prompt: reg query HKCR\CLSID | find /i "{9F3DBFEE-FD77-4774-868B-65F75E7DB7C3}"

A better answer would allow me to find the GUID directly from the file before it was registered. At least this way you can create a script to install and verify if it was successfully installed.

Solution 2:

I needed to check whether a DLL with particular name is registered and I used this command in my BAT:

reg query HKLM\SOFTWARE\Classes /s /f whatever.dll
if errorlevel 1 goto DLL_MISSING

If with errorlevel sent control to the label whenver reg query found nothing. You may need to change the part of the registry where you search (in my case HKLM'..., the more specific path the faster, otherwise it takes really long).

The output can be processed if necessary, GUID for the entry can be obtained, but that is out of scope of reg query command.