{"id":12291,"date":"2011-10-25T00:01:00","date_gmt":"2011-10-25T00:01:00","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/2011\/10\/25\/use-powershell-to-easily-find-the-key-property-of-a-wmi-class\/"},"modified":"2011-10-25T00:01:00","modified_gmt":"2011-10-25T00:01:00","slug":"use-powershell-to-easily-find-the-key-property-of-a-wmi-class","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/use-powershell-to-easily-find-the-key-property-of-a-wmi-class\/","title":{"rendered":"Use PowerShell to Easily Find the Key Property of a WMI Class"},"content":{"rendered":"

Summary:<\/strong> Learn how to find the key property of a WMI class by using a Windows PowerShell function.<\/p>\n

 <\/p>\n

Microsoft Scripting Guy Ed Wilson here. Well, I received a decent amount of feedback about version 1 of my HSGWMIhelper<\/b> Windows PowerShell module. Today, I want to add a needed feature to the module: I need the ability to find a WMI key property from a WMI class. I added the Get-WMIKey function to the Scripting Guys Script Repository<\/a>.<\/p>\n

One thing I often need is to be able to do is find the key property of a WMI class. For example, after I have imported my HSGWMImoduleV2<\/b> module, I can use the Get-WmiKey<\/b> function to retrieve the key property from the Win32_Process<\/b> WMI class. The handle<\/b> <\/i>property is the key property from the class. This is shown here:<\/p>\n

PS C:\\> Import-Module hsg*v2<\/p>\n

PS C:\\> Get-WmiKey win32_process<\/p>\n

I now start an instance of Notepad, and use the Get-Process<\/b> cmdlet to retrieve information about the Notepad process as shown here:<\/p>\n

PS C:\\> notepad<\/p>\n

PS C:\\> Get-Process notepad<\/p>\n

 <\/p>\n

Handles  <\/span>NPM(K)    <\/span>PM(K)      <\/span>WS(K) <\/span>VM(M)   <\/span>CPU(s)     <\/span>Id <\/span>ProcessName<\/p>\n

——-  <\/span>——    <\/span>—–      <\/span>—– <\/span>—–   <\/span>——     <\/span>— <\/span>———–<\/p>\n

     78       <\/span>9     <\/span>4272       <\/span> 8948    <\/span>86     <\/span>0.03   <\/span>6872 <\/span>notepad<\/p>\n<\/p>\n

I can then use the id<\/b> <\/i>property value (equals the handle<\/b> <\/i>property from WMI) with the [WMI]<\/b> instance accelerator to retrieve that specific instance of the Win32_Process<\/b> class. The following is the syntax for this command:<\/p>\n

[wmi]”win32_process.handle=6872″<\/p>\n

The command and associated output are shown in the following figure.<\/p>\n

\"Image<\/a><\/p>\n

One thing that is great about the WMI instance accelerator is that instance methods are immediately available. This technique is shown in the following code:<\/p>\n

([wmi]”win32_process.handle=6872″).terminate()<\/p>\n

The command and associated output are shown in the following figure.<\/p>\n

\"Image<\/a><\/p>\n

In the Get-WmiKey<\/b> function, the first thing I do is create help by using comment-based help (all the functions in my HSGWMIModuleV2<\/b> module have comment-based help). The help portion of the function is shown here.<\/p>\n

function Get-WmiKey<\/p>\n

{<\/p>\n

  <#<\/p>\n

   .Synopsis<\/p>\n

    This function returns the key property of a WMI class<\/p>\n

   .Description<\/p>\n

    This function returns the key property of a WMI class<\/p>\n

   .Example<\/p>\n

    Get-WMIKey win32_bios<\/p>\n

    Returns the key properties for the Win32_bios WMI class in root\\ciimv2<\/p>\n

   .Example<\/p>\n

    Get-WmiKey -class Win32_product<\/p>\n

    Returns the key properties for the Win32_Product WMI class in root\\cimv2<\/p>\n

   .Example<\/p>\n

    Get-WmiKey -class systemrestore -namespace root\\default<\/p>\n

    Gets the key property from the systemrestore WMI class in the root\\default<\/p>\n

    WMI namespace.<\/p>\n

   .Parameter Class<\/p>\n

    The name of the WMI class<\/p>\n

   .Parameter Namespace<\/p>\n

    The name of the WMI namespace. Defaults to root\\cimv2<\/p>\n

   .Parameter Computer<\/p>\n

    The name of the computer. Defaults to local computer<\/p>\n

   .Notes<\/p>\n

    NAME:  Get-WMIKey<\/p>\n

    AUTHOR: ed wilson, msft<\/p>\n

    LASTEDIT: 10\/18\/2011 17:38:20<\/p>\n

    KEYWORDS: Scripting Techniques, WMI<\/p>\n

    HSG: HSG-10-24-2011<\/p>\n

   .Link<\/p>\n

     Http:\/\/www.ScriptingGuys.com<\/p>\n

 #Requires -Version 2.0<\/p>\n

 #><\/p>\n

Next, I create the input parameters. I use parameter attributes to make the class<\/i> parameter mandatory, and I assign it to the first position. The remainder of the parameters use techniques I have written about in the past.<\/p>\n

Param(<\/p>\n

   [Parameter(Mandatory = $true,Position = 0)]<\/p>\n

   [string]$class,<\/p>\n

   [string]$namespace = “root\\cimv2”,<\/p>\n

   [string]$computer = $env:computername<\/p>\n

 )<\/p>\n

Now, I do something pretty cool (I use this technique in other functions in the HSGWmiModuleV2<\/b> module). I cast the string in the $class<\/b> variable to be an instance of a management object. I use parameter substitution to put together a complete path: computer name, WMI namespace, and WMI class name:<\/p>\n

[wmiclass]$class = “\\\\{0}\\{1}:{2}” -f $computer,$namespace,$class<\/p>\n

Now I obtain a collection of the properties of the class, and I expand the qualifiers associated with each property. I then look for the name that is equal to “key” and I print out the property names. It is important to note that some WMI classes have multiple keys, such as Win32_product<\/b>. This portion of the function is shown here:<\/p>\n

  $class.Properties |<\/p>\n

      Select-object @{Name=”PropertyName”;Expression={$_.name}} `<\/p>\n

        -ExpandProperty Qualifiers |<\/p>\n

      Where-object {$_.Name -eq “key”} |<\/p>\n

      ForEach-Object {$_.PropertyName}<\/p>\n

} #end GetWmiKey<\/p>\n

 <\/p>\n

I included the Get-WMiKey<\/b> function in the second version of my HSGWmiModuleV2<\/b> module. You will find the complete module on the Scripting Guys Script Repository<\/a>.<\/p>\n

 <\/p>\n

That’s it for now. See you tomorrow when I will add another really cool WMI function to my WMI module.<\/p>\n

I invite you to follow me on Twitter<\/a> and Facebook<\/a>. If you have any questions, send email to me at scripter@microsoft.com<\/a>, or post your questions on the Official Scripting Guys Forum<\/a>. See you tomorrow. Until then, peace.<\/p>\n<\/p>\n

Ed Wilson, Microsoft Scripting Guy<\/b><\/p>\n<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Summary: Learn how to find the key property of a WMI class by using a Windows PowerShell function.   Microsoft Scripting Guy Ed Wilson here. Well, I received a decent amount of feedback about version 1 of my HSGWMIhelper Windows PowerShell module. Today, I want to add a needed feature to the module: I need […]<\/p>\n","protected":false},"author":596,"featured_media":87096,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[3,4,45,6],"class_list":["post-12291","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scripting","tag-scripting-guy","tag-scripting-techniques","tag-windows-powershell","tag-wmi"],"acf":[],"blog_post_summary":"

Summary: Learn how to find the key property of a WMI class by using a Windows PowerShell function.   Microsoft Scripting Guy Ed Wilson here. Well, I received a decent amount of feedback about version 1 of my HSGWMIhelper Windows PowerShell module. Today, I want to add a needed feature to the module: I need […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/12291","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/users\/596"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/comments?post=12291"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/12291\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media\/87096"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media?parent=12291"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=12291"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=12291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}