Getting WMI objects with Get-CimInstance
This sample only applies to Windows platforms.
Windows Management Instrumentation (WMI) is a core technology for Windows system administration
because it exposes a wide range of information in a uniform manner. Because of how much WMI makes
possible, the PowerShell cmdlet for accessing WMI objects, Get-CimInstance, is one of the most
useful for doing real work. We're going to discuss how to use the CIM cmdlets to access WMI objects
and then how to use WMI objects to do specific things.
Listing WMI classes
The first problem most WMI users face is trying to find out what can be done with WMI. WMI classes describe the resources that can be managed. There are hundreds of WMI classes, some of which contain dozens of properties.
Get-CimClass addresses this problem by making WMI discoverable. You can get a list of the WMI
classes available on the local computer by typing:
Get-CimClass -Namespace root/CIMV2 |
Where-Object CimClassName -like Win32* |
Select-Object CimClassName
CimClassName
------------
Win32_DeviceChangeEvent
Win32_SystemConfigurationChangeEvent
Win32_VolumeChangeEvent
Win32_SystemTrace
Win32_ProcessTrace
Win32_ProcessStartTrace
Win32_ProcessStopTrace
Win32_ThreadTrace
Win32_ThreadStartTrace
Win32_ThreadStopTrace
...
You can retrieve the same information from a remote computer using the ComputerName parameter, specifying a computer name or IP address:
Get-CimClass -Namespace root/CIMV2 -ComputerName 192.168.1.29
The class listing returned by remote computers may vary due to the specific operating system the computer is running and the particular WMI extensions are added by installed applications.
Note
When using CIM cmdlets to connect to a remote computer, the remote computer must be running WMI and the account you are using must be in the local Administrators group on the remote computer. The remote system doesn't need to have PowerShell installed. This allows you to administer operating systems that aren't running PowerShell, but do have WMI available.
Displaying WMI class details
If you already know the name of a WMI class, you can use it to get information immediately. For example, one of the WMI classes commonly used for retrieving information about a computer is Win32_OperatingSystem.
Get-CimInstance -Class Win32_OperatingSystem
SystemDirectory Organization BuildNumber RegisteredUser SerialNumber Version
--------------- ------------ ----------- -------------- ------------ -------
C:\WINDOWS\system32 Microsoft 22621 USER1 00330-80000-00000-AA175 10.0.22621
Although we're showing all of the parameters, the command can be expressed in a more succinct way.
The ComputerName parameter isn't necessary when connecting to the local system. We show it to
demonstrate the most general case and remind you about the parameter. The Namespace defaults to
root/CIMV2, and can be omitted as well. Finally, most cmdlets allow you to omit the name of common
parameters. With Get-CimInstance, if no name is specified for the first parameter, PowerShell
treats it as the Class parameter. This means the last command could have been issued by typing:
Get-CimInstance Win32_OperatingSystem
The Win32_OperatingSystem class has many more properties than those displayed here. You can use Get-Member to see all the properties. The properties of a WMI class are automatically available like other object properties:
Get-CimInstance -Class Win32_OperatingSystem | Get-Member -MemberType Property
TypeName: Microsoft.Management.Infrastructure.CimInstance#root/cimv2/Win32_OperatingSystem
Name MemberType Definition
---- ---------- ----------
BootDevice Property string BootDevice {get;}
BuildNumber Property string BuildNumber {get;}
BuildType Property string BuildType {get;}
Caption Property string Caption {get;}
CodeSet Property string CodeSet {get;}
CountryCode Property string CountryCode {get;}
CreationClassName Property string CreationClassName {get;}
CSCreationClassName Property string CSCreationClassName {get;}
CSDVersion Property string CSDVersion {get;}
CSName Property string CSName {get;}
CurrentTimeZone Property int16 CurrentTimeZone {get;}
DataExecutionPrevention_32BitApplications Property bool DataExecutionPrevention_32BitApplications {get;}
DataExecutionPrevention_Available Property bool DataExecutionPrevention_Available {get;}
...
Displaying non-default properties with Format cmdlets
If you want the information contained in the Win32_OperatingSystem class that isn't displayed by default, you can display it by using the Format cmdlets. For example, if you want to display available memory data, type:
Get-CimInstance -Class Win32_OperatingSystem | Format-Table -Property TotalVirtualMemorySize, TotalVisibleMemorySize, FreePhysicalMemory, FreeVirtualMemory, FreeSpaceInPagingFiles
TotalVirtualMemorySize TotalVisibleMemorySize FreePhysicalMemory FreeVirtualMemory FreeSpaceInPagingFiles
---------------------- ---------------------- ------------------ ----------------- ----------------------
41787920 16622096 9537952 33071884 25056628
Note
Wildcards work with property names in Format-Table, so the final pipeline element can be
reduced to Format-Table -Property Total*Memory*, Free*
The memory data might be more readable if you format it as a list by typing:
Get-CimInstance -Class Win32_OperatingSystem | Format-List Total*Memory*, Free*
TotalVirtualMemorySize : 41787920
TotalVisibleMemorySize : 16622096
FreePhysicalMemory : 9365296
FreeSpaceInPagingFiles : 25042952
FreeVirtualMemory : 33013484
Name : Microsoft Windows 11 Pro|C:\Windows|\Device\Harddisk0\Partition2
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