Windows 7 / Getting Started

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Using WMI_Cmdlets

Windows Management Instrumentation is used on many administrator applications to automate the process of retrieving information on computers or taking action on computers.

As a simple example, different applications are used to deploy updates to clients, but they often fi rst checked to see if the update has already been deployed. WMI is used to query the computer to determine if the update is deployed. Applications such as Windows Server Update Services (WSUS), Microsoft Systems Management Server (SMS), and System Center Confi guration Manager (SCCM) all use WMI regularly.

PowerShell includes a full set of WMI cmdlets that can be used to retrieve information on systems just as they do on applications. One of the challenges with these is that there is so much that can be done that it's easy to get overwhelmed by the complexity. However, if you understand how a few of them work, you'll easily be able to use the concepts you've learned and branch off in different directions.

First, when querying WMI objects, you need to include an extra parameter that includes the class and the name of the object that you want to query. As an example, the Win32_ Share class includes the name of the class (Win32) and the name of the object type (Share). Classes and objects sometimes confuse people. You can think of a class as a blueprint, similar to a blueprint for a house. You can't live in a blueprint. Similarly, a class isn't an actual object but the defi nition for an object. When a folder is shared, it's viewed by WMI as a share object, and the Win32_Share class can be used to query information on this share object.

Note There are too many classes in the Win32 Class family to list here However, if you want to see a full list, check out this link: http://msdn.microsoft.com/library/aa394084.aspx

Win32 classes are the primary classes used to query and work with Windowsbased operating systems. There are hundreds of objects in this class, but here's a small sampling: Win32_Account, Win32_BIOS, Win32_ComputerSystem, Win32_SystemEvent, Win32_CurrentTime, Win32_DiskQuota, Win32_Group, Win32_LogicalDisk, Win32_ NetworkAdapter, Win32_NTEventLogFile, Win32_OperatingSystem, Win32_Printer, Win32_ Process, Win32_Service, and Win32_Session.

A logical question is, "What do each of these do?" The simplest answer is, "Ask PowerShell with a query."