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New-Variable

  • Reference
Module:
Microsoft.PowerShell.Utility

Creates a new variable.

Syntax

New-Variable
   [-Name] <String>
   [[-Value] <Object>]
   [-Description <String>]
   [-Option <ScopedItemOptions>]
   [-Visibility <SessionStateEntryVisibility>]
   [-Force]
   [-PassThru]
   [-Scope <String>]
   [-WhatIf]
   [-Confirm]
   [<CommonParameters>]

Description

The New-Variable cmdlet creates a new variable in Windows PowerShell. You can assign a value to the variable while creating it or assign or change the value after it is created.

You can use the parameters of New-Variable to set the properties of the variable (such as those that create read-only or constant variables), set the scope of a variable, and determine whether variables are public or private.

Typically, you create a new variable by typing the variable name and its value, such as "$var = 3", but you can use the New-Variable cmdlet to use its parameters.

Examples

Example 1

New-Variable days

This command creates a new variable named "days". It has no value immediately following the command.

Example 2

New-Variable zipcode -Value 98033

This command creates a variable named "zipcode" and assigns it the value "98033".

Example 3

PS> New-Variable -Name max -value 256 -Option ReadOnly
PS> New-Variable -Name max -value 1024

New-Variable : A variable with name 'max' already exists.
At line:1 char:1
+ New-Variable -Name max -Value 1024
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ResourceExists: (max:String) [New-Variable], SessionStateException
    + FullyQualifiedErrorId : VariableAlreadyExists,Microsoft.PowerShell.Commands.NewVariableCommand

PS> New-Variable -Name max -Value 1024 -Force

This example shows how to use the ReadOnly option of New-Variable to protect a variable from being overwritten.

The first command creates a new variable named Max and sets its value to "256". It uses the Option parameter with a value of ReadOnly.

The second command tries to create a second variable with the same name. This command returns an error, because the read-only option is set on the variable.

The third command uses the Force parameter to override the read-only protection on the variable. In this case, the command to create a new variable with the same name succeeds.

Example 4

PS> New-Variable -Name counter -Visibility Private

#Effect of private variable in a module.

PS> Get-Variable c*

Name                           Value
----                           -----
Culture                        en-US
ConsoleFileName
ConfirmPreference              High
CommandLineParameters          {}

PS C:\> $counter
"Cannot access the variable '$counter' because it is a private variable"
At line:1 char:1
+ $counter
+ ~~~~~~~~
    + CategoryInfo          : PermissionDenied: (counter:String) [], SessionStateException
    + FullyQualifiedErrorId : VariableIsPrivate

PS> Get-Counter

Name         Value
----         -----
Counter1     3.1415
...

This command demonstrates the behavior of a private variable in a module. The module contains the Get-Counter cmdlet, which has a private variable named "Counter". The command uses the Visibility parameter with a value of "Private" to create the variable.

The sample output shows the behavior of a private variable. The user who has loaded the module cannot view or change the value of the Counter variable, but the Counter variable can be read and changed by the commands in the module.

Example 5: Create a variable with a space

PS C:\> New-Variable -Name 'with space' -Value 'abc123xyz'

PS C:\> Get-Variable -Name 'with space'

Name                           Value
----                           -----
with space                     abc123xyz

PS C:\> ${with space}
abc123xyz

This command demonstrates that variables with spaces can be created. The variables can be accessed using the Get-Variable cmdlet or directly by delimiting a variable with braces.

Parameters

-Confirm

Prompts you for confirmation before running the cmdlet.

Type:SwitchParameter
Aliases:cf
Position:Named
Default value:False
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-Description

Specifies a description of the variable.

Type:String
Position:Named
Default value:None
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-Force

Allows you to create a new variable with the same name as an existing read-only variable.

By default, you can overwrite a variable unless the variable has an option value of ReadOnly or Constant. For more information, see the Option parameter.

Type:SwitchParameter
Position:Named
Default value:False
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-Name

Specifies a name for the new variable.

Type:String
Position:1
Default value:None
Required:True
Accept pipeline input:True
Accept wildcard characters:False

-Option

Sets the value of the Options property of the variable.

Valid values are:

  • None: Sets no options. ("None" is the default.)
  • ReadOnly: Can be deleted. Cannot be changed, except by using the Force parameter.
  • Constant: Cannot be deleted or changed. "Constant" is valid only when you are creating a variable. You cannot change the options of an existing variable to "Constant".
  • Private: The variable is available only in the current scope.
  • AllScope: The variable is copied to any new scopes that are created.

To see the Options property of all variables in the session, type "get-variable | format-table -property name, options -autosize".

Type:ScopedItemOptions
Position:Named
Default value:"None"
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-PassThru

Returns an object representing the new variable. By default, this cmdlet does not generate any output.

Type:SwitchParameter
Position:Named
Default value:No output
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-Scope

Specifies the scope of the new variable. The acceptable values for this parameter are:

  • Global. Variables created in the global scope are accessible everywhere in a PowerShell process.
  • Local. The local scope refers to the current scope, this can be any scope depending on the context.
  • Script. Variables created in the script scope are accessible only within the script file or module they are created in.
  • Private. Variables created in the private scope cannot be accessed outside the scope they exist in. You can use private scope to create a private version of an item with the same name in another scope.
  • A number relative to the current scope (0 through the number of scopes, where 0 is the current scope, 1 is its parent, 2 the parent of the parent scope, and so on). Negative numbers cannot be used.

Local is the default scope when the scope parameter is not specified.

For more information, see about_Scopes.

Type:String
Position:Named
Default value:Local
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-Value

Specifies the initial value of the variable.

Type:Object
Position:2
Default value:None
Required:False
Accept pipeline input:True
Accept wildcard characters:False

-Visibility

Determines whether the variable is visible outside of the session in which it was created. This parameter is designed for use in scripts and commands that will be delivered to other users.

Valid values are:

  • Public: The variable is visible. ("Public" is the default.)
  • Private: The variable is not visible.

When a variable is private, it does not appear in lists of variables, such as those returned by Get-Variable, or in displays of the Variable: drive. Commands to read or change the value of a private variable return an error. However, the user can run commands that use a private variable if the commands were written in the session in which the variable was defined.

Type:SessionStateEntryVisibility
Position:Named
Default value:Public
Required:False
Accept pipeline input:False
Accept wildcard characters:False

-WhatIf

Shows what would happen if the cmdlet runs. The cmdlet is not run.

Type:SwitchParameter
Aliases:wi
Position:Named
Default value:False
Required:False
Accept pipeline input:False
Accept wildcard characters:False

Inputs

Object

You can pipe a value to New-Variable.

Outputs

None or System.Management.Automation.PSVariable

When you use the PassThru parameter, New-Variable generates a System.Management.Automation.PSVariable object representing the new variable. Otherwise, this cmdlet does not generate any output.