Variable in PowerShell

Introduction to Variable in PowerShell

The variable in PowerShell is a block of memory that can be used to store values. PowerShell variables are denoted using the “$” symbol. A variable name can be anything from numbers, alphabets or even underscores. PowerShell variables are not case sensitive. PowerShell variables are not just text-based, instead, they are objects like that of Microsoft.Net objects.

Creation of Variables with Syntax

The below example shows the creation of a variable

$test

$test is a variable and it can be assigned a value using the = or assignment operator

$test=” This is a variable”

To get the value of a variable, we just need to simply enter the variable

Example #1

The following example is used to show introduction to variable

Code:

Write-Host "Introduction to the variable"
$test="This is a variable"
Write-Host "The value of the variable is below"
$test

Output:

Introduction to variable

The value of the variable is below

This is a variable

Example #2

The following example is used to show arithmetic operations on a variable

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Code:

Write-Host "Example of arithmetic operation"
$v1 = 11111
$v2 = 3333454
$v3 = $v1 + $v2
$v3

Output:

Example of arithmetic operation

3344565

Variable Types in PowerShell

In PowerShell, if the datatype of the variable is not specified, PowerShell automatically detects the variable type when the variable is initialized.

The following are the types of the array variable

1. Array: An array variable is the first type of variable. An array variable can be declared as follows

[int32[]]$inttest = 1,2,3,4

or

$test=1..99

2. Bool: A Boolean variable can be defined as follows.

[bool] $test = 1
Or

[bool] $test= $true

3. DateTime: A datetime variable can be declared as follows

$a = [DateTime] "07/06/2015 05:00 AM"

4. Guid: A guid value can be assigned to a variable as follows

$a=New-Guid

5. HashTable: The hashtable variable is storing a key-value pair. A hashtable can be defined as follows

$test = @{ key1= 1; key2= 2; key3= 3}

or

$test = @{}

6. PSObject: A PSobject variable is similar to the hashtable and uses a key-value pair structure. It can be defined as follows.

$test = [PSCustomObject]@{
Key1 = 'Value1'
Key2 = 'Value2'
}

Automatic Variables in PowerShell

These variables are created by PowerShell itself. They are used to maintain the state of the PowerShell. Users will not change the value of these variables and PowerShell changes them to maintain accuracy. The following are some of the automatic variables.

All the automatic variable is PowerShell can be found by running the below command.

Code:

Get-Variable

Output:

Different Types of Variable Scopes

The scope is nothing but the life shell of a variable. A variable is alive only within the scope specified.

• $Global: A variable is available throughout the script in the current session.
• $Script: The variable is accessible only inside the script and is discarded after the script is finished executing.
• $Private: Variable is valid only within a function.
• $local: Variable is valid only in the current scope of the session.
• Cmdlets associated with variables:
• Clear-Variable: Deletes the value of a variable
• Get-Variable: Gets the list of variables that are present in the current session.
• New-Variable: Used to create a new variable
• Remove-Variable: Deletes the variable
• Set-Variable: Used to change the value of a variable

Examples #1

To check if the last ran cmdlet was successful or not.

Code:

$? is used for the above-said purpose

The previous cmdlet ran

get-mynae

Corresponding output

As it is evident from the above, the cmdlet execution was unsuccessful. After that, the cmdlet was executed.

Code

$?

Output:

False denotes the last cmdlet was unsuccessful and true denotes successful execution.

Example #2

To Store the value of a variable to a word or csv file

Code:

Write-Host "variable example"
$test = "First variable"
$test1 = "second variable"
$test2 = "third variable"
$test3 = "fourth variable"
$test | Out-File C:\test.txt -Append
$test1 | Out-File C:\test.txt -Append
$test2 | Out-File C:\test.txt -Append
$test3 | Out-File C:\test.txt -Append

Output:

Example #3

Set and Get a Variable

Code:

Set-Variable -Name "test" -Value "test"
Get-Variable -Name "test"
Set-Variable -Name "test1" -Value "testone"
Get-Variable -Name "test1"
Set-Variable -Name "test2" -Value "testtwo"
Get-Variable -Name "test2"
Write-Host "Get all the user defined variables in the current session"
Get-Variable test* -ValueOnly

Output:

Conclusion

Thus, the articles covered in detail about variables in PowerShell. It also explained the data types associated with a variable, variable scope and the types of variables that are available in PowerShell. To understand much deeper about variables it is advisable to create sample programs and have fun working around them.

Recommended Articles

This is a guide to Variable in PowerShell. Here we discuss how to create variables, different Types of Variable Scopes and automatic variables in PowerShell along with the examples. You can also go through our other suggested articles to learn more–

1. PowerShell Move-Item
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3. Comparison Operators in PowerShell
4. Loops in PowerShell
5. PowerShell Out-File | Examples and Parameters