Exploring PowerShell continues. Today, we will discuss PowerShell variables in depth.

• A variable is a unit of memory in which values are stored.
• We can store all types of values in PowerShell variables.
  • For example
    • the results of commands.
    • names, paths, settings, and values.
• In PowerShell, variables are represented by text strings that begin with a dollar sign ($).
  • Example: $var, $process_var, or $my_var.
• In PowerShell variables are not case-sensitive.
  • This means $var is same as $Var or is same as $VAR
  • Example – assign some value to variable var.
    • Say, $var= “LIFE IS BEAUTIFUL”.
  • Print the value for $var, $Var and $VAR and see the result.
  • Result will be same for all the three variables.

• PowerShell variable names can include – spaces and special characters.
• We could store the complete PowerShell CMDLET result to PowerShell variable.

PS C:\> $processdetails = Get-Process
PS C:\> $processdetails

PowerShell Variable Scopes

• By default, variables are only available in the scope in which they’re created.
  • For example, variable created in a function is available within the function.
  • A variable created in a script is available within the script.
• PowerShell has following different scopes
  • Global – The root scope. These variables are available across the current session, console or runspace.
  • Local – The current executing context.
    • If we are inside function, our local scope is function.
    • If we are running commands in console prompt, scope is the global scope.
  • Script – These variables are only accessible within the script.
• Examples :

$global:global_var = "Global Variable"
$script:script_var = "Script Variable"
$local:local_var = "Local Variable"

Data Type of PowerShell variable

• By default, PowerShell is dynamically typed. This means, PowerShell automatically determines the type based the value assigned to it.
• We can append “GetType().Name” to the variable to know the type.
• Example

PS C:\> $var = "LIFE IS BEAUTIFUL"
PS C:\> $var.GetType().Name
String
PS C:\> $var_int = 09
PS C:\> $var_int.GetType().Name
Int32
PS C:\>

• We can force a variable to accept only specific data type by specifying type name before the variable.
• Example

[int]$int_var = 10

• If we try to assign another type value PowerShell throws an error.
• Example: Here we will try to assign string value to variable $int_var

$var="LIFE IS BEAUTIFUL"

• We will get a following error

MetadataError: Cannot convert value “LIFE IS BEAUTIFUL” to type “System.Int32”. Error: “The input string ‘LIFE IS BEAUTIFUL’ was not in a correct format.”

Few PowerShell variable CMDLETs

• Get-Variable
  • List all variables in the session

• Clear-Variable
  • Deletes the value inside a variable.
  • Setting it to $null.
  • But preserves the variable structure.
  • Example: Below code clears the value of variable – var

PS C:\> Clear-Variable
cmdlet Clear-Variable at command pipeline position 1
Supply values for the following parameters:
Name[0]: var
PS C:\> $var
PS C:\>

• Remove-Variable
  • Completely deletes the variable and its value from memory.
  • We could again execute the PowerShell CMDLET – Get-Variable and check the variable is removed or not.

Remove-Variable -Name var

• Set-Variable
  • Though we can directly set the value to variable by using assignment operator.
  • We can also use the CMDLET “Set-Variable” to set / update the value.
  • Set-Variable CMDLET also allows us to set the description of the variable.
  • Example

Set-Variable -Name "KnowledgeJunctionTenantURL" 
             -Description "This variable holds the KnowledgeJunction tenant URL"

Types of Variables in PowerShell

• User-created variables
  • These are the variables created and maintained by the users.
• Automatic variables
  • These variables stores the state of PowerShell.
  • These variables are created by PowerShell.
  • PowerShell changes the values as required.
  • Users can not change the values of these variables.
  • Examples:
    • $Error : Array of error object, contains most recent errors.
    • $foreach : Enumerator of a foreach loop
    • $Host : Contains an object that represents the current host application for PowerShell.
• Preference variables
  • Preference variables store user preferences for PowerShell.
  • These variables are created by PowerShell and are populated with default values.
  • Users can change the values of these variables

REFERENCES:

• PowerShell Variables
• PowerShell Automatic Variables
• PowerShell Preference Variables

If you new to PowerShell, take look to our PowerShell articles.

Thank you for reading.

Feel free to discuss anything about PowerShell. Have a great time ahead! LIFE IS BEAUTIFUL :)