{"id":3655,"date":"2013-05-11T00:01:00","date_gmt":"2013-05-11T00:01:00","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/2013\/05\/11\/weekend-scripter-playing-with-powershells-get-variable-cmdlet\/"},"modified":"2013-05-11T00:01:00","modified_gmt":"2013-05-11T00:01:00","slug":"weekend-scripter-playing-with-powershells-get-variable-cmdlet","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/weekend-scripter-playing-with-powershells-get-variable-cmdlet\/","title":{"rendered":"Weekend Scripter: Playing with PowerShell's Get-Variable Cmdlet"},"content":{"rendered":"

Summary<\/strong>: Microsoft Scripting Guy, Ed Wilson, spends some time playing around with the <\/span>Get-Variable<\/strong> cmdlet.<\/span><\/p>\n

Microsoft Scripting Guy, Ed Wilson, is here. This morning I am doing something a little different. Instead of drinking English Breakfast tea, I woke up feeling like I wanted Oolong tea instead. So I made a pot of Oolong tea with a spoonful of jasmine buds, a half spoon of peppermint leaves, three juniper berries, and half of a crushed cinnamon stick. It is quite invigorating, without being too overbearing.<\/p>\n

Checking the value of a variable<\/h2>\n

So I am sitting on the lanai in my porch swing, and I just finished checking the email for the scripter@microsoft.com<\/a> email alias. I received an email asking why I would bother using the Get-Variable<\/strong> cmdlet, when I can simply reference the variable to see the value? The reason is that there are many more things I need to do with variables than simply see the value contained inside the variable. The following example assigns a directory listing to the $dir<\/strong> variable:<\/p>\n

$dir = dir -Directory | ? lastwritetime -gt $([datetime]’4\/1\/13′)<\/p>\n

To see the value that is contained in the $dir<\/strong> variable, I can type $dir<\/strong>. The command and the output are shown in the image that follows.<\/p>\n

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

Use Get-Variable<\/h3>\n

I can also do this by using the Get-Variable<\/strong> cmdlet. When use Get-Variable<\/strong>, both the name and the value appear. To return only the value, I group the expression, and get the Value<\/strong> <\/em>property as shown here:<\/p>\n

(Get-Variable dir).value<\/p>\n

This command and the associated output are shown in the image that follows.<\/p>\n

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

Use the Variable provider<\/h3>\n

But there are other ways to retrieve values from Windows PowerShell variables. For example, I can use the Variable<\/strong> provider and access the value from the Windows PowerShell Variable drive. I do this by using the command shown here:<\/p>\n

$variable:dir<\/p>\n

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

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

Because the Variable<\/strong> provider creates a PSDrive named Variable<\/strong>, I can use the standard Windows PowerShell cmdlets to work with the variable. For example, I can use Get-Item <\/strong>as shown in this example:<\/p>\n

Get-Item -Path Variable:\\dir<\/p>\n

But if I only want the value of the Dir<\/strong> variable, I need to select the Value<\/strong> property:<\/p>\n

(Get-Item -Path Variable:\\dir).value<\/p>\n

The commands and associated output are shown in the image that follows.<\/p>\n

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

One of the cooler things to do is to use the Get-Content<\/strong> cmdlet to obtain the contents of the variable. When using this technique, only the first value from the array returns. This is shown here:<\/p>\n

PS C:\\> Get-Content variable:\\dir<\/p>\n

 <\/p>\n

    Directory: C:\\<\/p>\n

 <\/p>\n

Mode                LastWriteTime     Length Name<\/p>\n

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

d—-         4\/23\/2013  12:41 PM            fso<\/p>\n

Examining the type of a variable<\/h2>\n

I am sure you know that there are different types of variables in Windows PowerShell. If I use the Get-Variable<\/strong> cmdlet, pipe the results to the Format-List<\/strong> cmdlet, and choose all of the properties, I obtain some pretty interesting information. This is shown here:<\/p>\n

PS C:\\> Get-Variable dir | fl *<\/p>\n

 <\/p>\n

PSPath        : Microsoft.PowerShell.Core\\Variable::dir<\/p>\n

PSDrive       : Variable<\/p>\n

PSProvider    : Microsoft.PowerShell.Core\\Variable<\/p>\n

PSIsContainer : False<\/p>\n

Name          : dir<\/p>\n

Description   :<\/p>\n

Value         : {fso, fsox, Program Files, Program Files (x86)…}<\/p>\n

Visibility    : Public<\/p>\n

Module        :<\/p>\n

ModuleName    :<\/p>\n

Options       : None<\/p>\n

Attributes    : {}<\/p>\n

If I take the $dir<\/strong> variable and pipe it to the Get-Member<\/strong> cmdlet, it returns information about the objects that are contained in the variable, and not about the variable itself.<\/p>\n

$dir | get-member<\/p>\n

The command and output from the command are shown in the image that follows.<\/p>\n

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

To find information about the variable itself, I use Get-Variable<\/strong> to return the variable, and then I pipe the result to the Get-Member<\/strong> cmdlet:<\/p>\n

Get-Variable dir | Get-Member<\/p>\n

The command and output from the command are shown here.<\/p>\n

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

Finding different types of variables<\/h2>\n

Unfortunately, this does not return anything about the type of Windows PowerShell variable. So what is the easy way to find the variable type? Use the Get-Variable<\/strong> cmdlet and pipe the returned objects to the Get-Member<\/strong> cmdlet. Next, I select only the TypeName<\/strong> property, and I use the Unique<\/strong> switch to ensure only unique instances return. Here is the command and the results:<\/p>\n

PS C:\\> Get-Variable | Get-Member | select typename -Unique<\/p>\n

 <\/p>\n

TypeName<\/p>\n

——–<\/p>\n

System.Management.Automation.PSVariable<\/p>\n

System.Management.Automation.QuestionMarkVariable<\/p>\n

System.Management.Automation.LocalVariable<\/p>\n

System.Management.Automation.SessionStateCapacityVariable<\/p>\n

System.Management.Automation.NullVariable<\/p>\n

When I know the different types of variables, I can use Windows PowerShell to list a particular type of variable. To do this, I pipe the results of Get-Variable<\/strong> to the Where-Object<\/strong>. In my Where-Object<\/strong> filter, I use the PSObject<\/strong> <\/em>property so I can reference the underlying type. This technique is shown here where I find all variables of the type LocalVariable<\/strong>. <\/em><\/p>\n

Get-Variable | where {$_.psobject.typenames -match ‘local’}<\/p>\n

The command and output from the command are shown here.<\/p>\n

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

Join me tomorrow for the exciting conclusion to the Windows PowerShell and Security series by Yuri Diogenes and Tom Schinder. To catch up, read the two previous posts in this series<\/a>.<\/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

Ed Wilson, Microsoft Scripting Guy<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Summary: Microsoft Scripting Guy, Ed Wilson, spends some time playing around with the Get-Variable cmdlet. Microsoft Scripting Guy, Ed Wilson, is here. This morning I am doing something a little different. Instead of drinking English Breakfast tea, I woke up feeling like I wanted Oolong tea instead. So I made a pot of Oolong tea […]<\/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":[3,4,61,45],"class_list":["post-3655","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scripting","tag-scripting-guy","tag-scripting-techniques","tag-weekend-scripter","tag-windows-powershell"],"acf":[],"blog_post_summary":"

Summary: Microsoft Scripting Guy, Ed Wilson, spends some time playing around with the Get-Variable cmdlet. Microsoft Scripting Guy, Ed Wilson, is here. This morning I am doing something a little different. Instead of drinking English Breakfast tea, I woke up feeling like I wanted Oolong tea instead. So I made a pot of Oolong tea […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/3655","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=3655"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/3655\/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=3655"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=3655"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=3655"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}