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Clear-Variable

  • Reference
Module:
Microsoft.PowerShell.Utility

Deletes the value of a variable.

Syntax

Clear-Variable
     [-Name] <String[]>
     [-Include <String[]>]
     [-Exclude <String[]>]
     [-Force]
     [-PassThru]
     [-Scope <String>]
     [-WhatIf]
     [-Confirm]
     [<CommonParameters>]

Description

The Clear-Variable cmdlet deletes the data stored in a variable, but it does not delete the variable. As a result, the value of the variable is NULL (empty). If the variable has a specified data or object type, this cmdlet preserves the type of the object stored in the variable.

Examples

Example 1: Remove the value of global variables that begin with a search string

Clear-Variable my* -Scope Global

This command removes the value of global variables that have names that begin with my.

Example 2: Clear a variable in a child scope but not the parent scope

$a=3
&{ Clear-Variable a }
$a

3

These commands demonstrate that clearing a variable in a child scope does not clear the value in the parent scope. The first command sets the value of the variable $a to 3. The second command uses the invoke operator (&) to run the Clear-Variable command in a new scope. The variable is cleared in the child scope (although it did not exist), but it is not cleared in the local scope. The third command, which gets the value of $a, shows that the value 3 is unaffected.

Example 3: Delete the value of the specified variable

Clear-Variable -Name "Processes"

This command deletes the value of the variable named Processes. After the cmdlet completes the operation, the variable named Processes still exists, but the value is null.

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

-Exclude

Specifies an array of items that this cmdlet omits in the operation. The value of this parameter qualifies the Name parameter. Enter a name element or pattern, such as "s*". Wildcards are permitted.

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

-Force

Allows the cmdlet to clear a variable even if it is read-only. Even using the Force parameter, the cmdlet cannot clear constants.

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

-Include

Specifies an array of items that this cmdlet includes in the operation. The value of this parameter qualifies the Name parameter. Enter a name element or pattern, such as "s*". Wildcards are permitted.

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

-Name

Specifies the name of the variable to be cleared. Wildcards are permitted. This parameter is required, but the parameter name Name is optional.

Type:String[]
Position:0
Default value:None
Required:True
Accept pipeline input:True
Accept wildcard characters:True

-PassThru

Returns an object representing the item with which you are working. By default, this cmdlet does not generate any output.

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

-Scope

Specifies the scope in which this alias is valid.

The acceptable values for this parameter are:

  • Global
  • Local
  • Script

You can also use a number relative to the current scope (0 through the number of scopes, where 0 is the current scope and 1 is its parent). Local is the default. For more information, see about_Scopes.

Type:String
Position:Named
Default value:None
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

None

You can't pipe objects to this cmdlet.

Outputs

None

By default, this cmdlet returns no output.

PSVariable

When you use the PassThru parameter, this cmdlet returns a PSVariable object representing the cleared variable.

Notes

Windows PowerShell includes the following aliases for Clear-Variable:

  • clv

  • To delete a variable, along with its value, use Remove-Variable or Remove-Item.

    This cmdlet does not delete the values of variables that are set as constants or owned by the system, even if you use the Force parameter.

    If the variable that you are clearing does not exist, the cmdlet has no effect. It does not create a variable with a null value.