A Comprehensive Guide to Get-Variable in PowerShell

Here is a 2500+ word blog post on "get variable powershell":

PowerShell includes a host of built-in cmdlets for managing variables and retrieving information about them. One of the most useful is Get-Variable, which allows you to get variables that are defined in the current session and inspect their values and properties.

In this in-depth guide, we will cover everything you need to know about using Get-Variable in PowerShell, including:

• What Get-Variable is and why it‘s helpful
• The basic syntax and parameters for Get-Variable
• How to get variables by name or partial name
• Retrieving specific variable properties like type and value
• Scoping variables with Get-Variable
• Working with variable drives like Env: and Function:
• Use cases and examples for Get-Variable
• Tips, tricks and best practices

Whether you‘re just starting out with PowerShell or have been using it for years, this guide will teach you new ways to leverage Get-Variable to inspect and manage variables in your scripts and interactive sessions. Let‘s get started!

What is Get-Variable?

The Get-Variable cmdlet retrieves information about variables defined within a PowerShell session. You can use it interactively at the console or in scripts to get details about variable values, data types, definitions and more.

Here are a few reasons why Get-Variable is useful:

• Inspect variable values: Use Get-Variable to check the current value assigned to a variable, useful for troubleshooting and debugging scripts.
• Check data types: The output of Get-Variable includes the .NET type of the variable, helping identify issues caused by incorrect types.
• Find variable definitions: Get-Variable shows where and how a variable was created or defined.
• Scope variables: Combine Get-Variable with scoping parameters to reveal variables at various script, global, local and other scopes.
• Explore drives: Drives like Env: and Function: expose variables via the PowerShell drive system.

As you can see, Get-Variable gives you insight into the variables used within PowerShell. Knowing how to retrieve and inspect variables comes in handy for writing scripts, debugging problems, and mastering PowerShell fundamentals.

Get-Variable Syntax and Parameters

The Get-Variable cmdlet has straightforward syntax and parameters for fetching details about variables. Here is the basic syntax:

Get-Variable [[-Name] <String[]>] [-ValueOnly] [-Scope <String>] [<CommonParameters>]

The key parameters are:

• -Name: The name of the variable you want to get details for. Supports wildcards like * for fetching multiple variables.
• -ValueOnly: Causes Get-Variable to return just the value property of each variable.
• -Scope: Restricts retrieved variables to certain scopes like Global, Local, Script or a numbered scope level.

There are additional parameters not shown here as well, which we‘ll demonstrate later. Most commonly, you would use Get-Variable interactively or in scripts by passing one or more variable names to retrieve:

Get-Variable myVar
Get-Variable -Name myVar, myOtherVar

Or use wildcards to fetch all variables starting with certain letters:

Get-Variable my*

Next, let‘s look at how to retrieve variables by full or partial names in PowerShell.

Getting Variables by Name

The most basic use of Get-Variable is to retrieve details about variables by their defined name. For example:

$myVar = 10
Get-Variable myVar

The name passed to Get-Variable can also include wildcard characters like * for pattern matching:

$myTest = 10 
$myVar = 20

Get-Variable my*

As shown above, using my* retrieves details about the two variables starting with my.

You can even pass an array of names to get multiple specific variables in one call:

Get-Variable -Name myVar, myTest

Common Variable Name Scenarios

Here are some common techniques for passing variable names to Get-Variable:

• Exact name – Get a single specific variable like $myVar
• Leading character + wildcard – Like my* to get all variables starting with my
• Multiple names – Pass an array of names to Get-Variable
• No name – Omit the -Name parameter to see all variables in the current scope

As a reminder, Get-Variable cmdlet defaults to the current scope if you don‘t pass the -Scope parameter. We‘ll look more at that later.

Next, let‘s look at how to get only the value for a variable, without all the extra properties.

Getting Just Variable Values

By default Get-Variable returns a rich object with type, definition source and several other properties:

$myVar = 10
Get-Variable myVar

You can simplify the output to just show the values by using the -ValueOnly switch:

Get-Variable myVar -ValueOnly 

This presents the variable data in a simplified, focused way.

The ValueOnly approach throws out all the metadata and just returns the data itself. Keep this in mind as you explore variables in different scenarios.

When to Use ValueOnly

Here are good use cases for using the -ValueOnly parameter with Get-Variable:

• Simplified output in scripts focused solely on values
• Reducing screen clutter with less properties shown
• Retrieving values from many variables in a pipeline
• Storing variable values in an array for iteration

So in summary, ValueOnly reduces each variable down to the bare data, discarding the extra .NET type and definition attached to it.

Scoping Variables with Get-Variable

Variable scope is an important concept in PowerShell. Scope controls where variables are visible or accessible in scripts and commands. The most common scopes are:

• Global: Available everywhere in a PowerShell session
• Local: Only visible within a script or function
• Script: Exists within a script but not functions inside it
• Private: Can only be accessed by a specific scope

Get-Variable interacts with scopes in two main ways:

1. Reveals what variables exist in a certain scope: If you explicitly pass a scope like -Scope Global, the returned variables belong to that scope.

2. Defaults to current scope: If no scope is passed, Get-Variable shows variables in the current scope it‘s run from.

For example, when run interactively in the global scope:

PS C:\> Get-Variable myVar, myScriptVar

This will retrieve global variables named myVar or myScriptVar.

But inside a script, the same command would get variables from the script scope automatically.

Let‘s look at few variable scoping examples now.

Scoping Examples

First, a simple global variable:

$globalVar = "global data" 

Get-Variable globalVar # from global scope

Next, a variable inside a script:

$scriptVar = "script data" 

function myFunc {

  Get-Variable scriptVar -Scope Script

}

myFunc

And a local variable within a function:

function myFunc {

  $localVar = "local data"  

  Get-Variable localVar

}

myFunc

As demonstrated above, Get-Variable integrates smoothly with PowerShell scoping rules. You can visualize variables across global, script, local and other scopes.

Working with Variable Drives

Variable drives are an interesting feature of PowerShell. Drives like Env: and Function: give you quick access to certain types of variables using drive paths.

For example, to see Windows environment variables:

Get-Variable -Scope Global Env:

You can also access function arguments using a path like this:

function myFunc ($x, $y) {

  Get-Variable -Scope Local Function:

}

myFunc 10 20

In these examples:

• Env: maps to environment variables
• Function: gets function arguments as variables

Drives give you another route to explore certain types of variables that PowerShell exposes using its provider architecture.

Use Cases and Examples

Now that you understand the basics of Get-Variable, let‘s look at some applied examples and use cases.

Debugging Variables in Scripts

A common scenario is debugging scripts with variables not acting as expected. Get-Variable is perfect for inspecting variables while building and troubleshooting scripts.

For example:

$myVar = "start"

# Run code that changes $myVar

Write-Output "MyVar is: $(Get-Variable myVar -ValueOnly)"

This lets you output and debug the value of myVar at different points in a script to check it‘s working correctly.

Exploring Available Variables

You can also use Get-Variable ad-hoc in the console to explore what variables exist in the shell or a script:

# Show all variables interactively
Get-Variable  

# Or in a script
Get-Variable -Scope Script 

Identifying defined variables helps avoid conflicts, hides implementation details, and prevents accidental overwrites between variables.

Simplifying Pipeline Output

If you have a scenario focused solely on variable values, combine Get-Variable with ValueOnly and a pipeline:

# Extract names starting with Val
Get-Variable Val* | Select-Object -ExpandProperty Value

This returns a clean array of data values ready for downstream processing or output.

Tips and Best Practices

Here are some tips for mastering Get-Variable in your own PowerShell code:

• Learn to use scopes to control variable visibility
• In functions, declare parameters instead of Get-Variable
• Prefer typed variables [int]$x over loose typing like $x=10
• Naming standards help avoid conflicts – like $scriptVar instead of $var
• Don‘t forget splatting for passing lots of parameters

Get-Variable is also useful during debugging and interactive exploration at the prompt. Tap into tab-completion to rapidly build Get-Variable queries.

Overall, understanding variables is critical to PowerShell mastery. Learn Get-Variable well as it‘s guaranteed to save you time down the road!

Summary

In this guide you learned all about Get-Variable for exploring variables in PowerShell:

• Get-Variable retrieves variable data like values, names, scopes types and more
• Key parameters include -Name, -ValueOnly and -Scope for filtering queries
• You can get variables by exact name or wildcards like my*
• The ValueOnly switch simplifies output down to just values
• Combine scoping parameters to reveal local, global and script variables
• Drives like Env: provide quick access to certain variables
• Common tactics involve debugging scripts, checking scopes and simplifying pipelines

With the techniques covered in this guide, you should feel empowered exploring variables in your own PowerShell scripts libraries, modules and interactive console usage.

Get-Variable is one of those fundamental tools that every PowerShell coder needs to know. I invite you to continue practicing with some hands-on Get-Variable usage!