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Connecting to WMI with VBScript

  • Artikkeli

WMI scripts can condense many of the steps required in a C++ program. They can connect to WMI, not only through an SWbemLocator object, but also through the moniker "winmgmts:". A moniker is a short name that locates a namespace, class, or instance in WMI. The name "winmgmts:" is the WMI moniker that tells the Windows Script Host to use the WMI objects, connects to the default namespace, and obtains an SWbemServices object. Other connection information, such as an impersonation level or a specific class or instance, appears in the string following the moniker name. You can use monikers in calls that either create or get WMI objects. For more information, see Constructing a Moniker String.

The following procedure describes how to connect to WMI using SWbemLocator.

To connect to WMI using SWbemLocator

  1. Retrieve a locator object with a call to CreateObject.

    Set Locator = CreateObject("WbemScripting.SWbemLocator")

  2. Log on to the namespace using a call to the ConnectServer method.

    Set objLocator = CreateObject("WbemScripting.SWbemLocator")
Set objService = objLocator.ConnectServer(".", "root\cimv2")

    If you do not specify a computer in the call to ConnectServer, then WMI connects to the local computer. If you do not specify a namespace, then WMI connects to the namespace specified in the registry key.

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\Scripting\Default Namespace

    The default namespace is \root\cimv2. For more information about namespaces, see Creating Hierarchies Within WMI.

  3. Set the impersonation level with a call to the SWbemServices.Security_ method.

    objService.Security_.ImpersonationLevel = 3

    For more information, see Setting the Default Process Security Level Using VBScript.

  4. Implement the purpose of your script.

    WMI exposes a variety of scripting objects that use to access and manipulate data across your network. For more information, see Manipulating Class and Instance Information and Scripting API for WMI.

    Set objLocator = CreateObject("WbemScripting.SWbemLocator")
Set objService = objLocator.ConnectServer(".", "root\cimv2")
objService.Security_.ImpersonationLevel = 3
Set Jobs = objService.ExecQuery("SELECT * FROM Win32_ScheduledJob")
i=0
For each Job in Jobs
    i = i+1   
    WScript.Echo Job.JobId & "  " & Job.Command & VBNewLine
Next
If i = 0 Then
    WScript.Echo "No Jobs Scheduled with the AT command were found"
End If

The following procedure describes how to connect to WMI and retrieve an object using a moniker.

To connect to WMI and retrieve an object using a moniker

  1. Call GetObject with a moniker in the input parameter.

    'the simple version
Set MyObject = GetObject("winMgmts::Win32_scheduledJob")

'Or the more complex version
strComputer = "."
Set MyObject = GetObject("winMgmts:{impersonationLevel=impersonate}!\\" & strComputer & "\Root\CIMv2:Win32_ScheduledJob")

    The moiniker contains a number of elements that you can use to connect to WMI:

    • The "winmgmts:" tells WSH to use Scripting API objects. In this particular example, the WSH will know that it should return an SWbemObject that describes the first Win32_scheduledJob on the system. Other possible objects to return would be an SWbemCollection or an SWbemServices object, depending on what the moniker described.

    • You can optionally set the security levels for the connection. Note that you cannot set name and password information in a moniker, however. For more information, see Securing Scripting Clients.

    • You can optionally define the path to the WMI object. This includes either the local or remote computer, the namespace, as well as the name of the class. For more information about using the VBScript GetObject in WMI scripts, see Creating an Instance and Retrieving a WMI Instance.

  2. Instead of retrieving a single item or collection, you can also choose to retrieve the SWbemServices object (as described in the previous example). Afterwards, you can then call additional queries on the returned object.

    strComputer = "."
Set objWMIService = GetObject("winmgmts:{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set colScheduledJobs = objWMIService.ExecQuery("Select * from Win32_ScheduledJob")
For Each objJob in colScheduledJobs
    Wscript.Echo "Job ID: " & objJob.JobId & "Command: " & objJob.Command & VBNewLine
Next

    In the previous example, impersonate, or impersonationLevel=3, is the default process security level. In the following example, it is not necessary to specify this process security level unless you need to change the process security to delegate. For more information, see Setting the Default Process Security Level Using VBScript.

Scripting in WMI