Clear-Variable
Deletes the value of a variable.
语法
Default （默认值）
Clear-Variable
[-Name] <String[]>
[-Include <String[]>]
[-Exclude <String[]>]
[-Force]
[-PassThru]
[-Scope <String>]
[-WhatIf]
[-Confirm]
[<CommonParameters>]
说明
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.
示例
Example 1: Remove the value of global variables that begin with a search string
PS C:\> 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
PS C:\> $a=3
PS C:\> &{ Clear-Variable a }
PS C:\> $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
PS C:\> 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.
参数
-Confirm
Prompts you for confirmation before running the cmdlet.
参数属性
| 类型: | SwitchParameter |
| 默认值: | False |
| 支持通配符: | False |
| 不显示: | False |
| 别名: | cf |
参数集
(All)
| Position: | Named |
| 必需: | False |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | False |
| 来自剩余参数的值: | 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.
参数属性
| 类型: | String[] |
| 默认值: | None |
| 支持通配符: | True |
| 不显示: | False |
参数集
(All)
| Position: | Named |
| 必需: | False |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | False |
| 来自剩余参数的值: | False |
-Force
Allows the cmdlet to clear a variable even if it is read-only. Even using the Force parameter, the cmdlet cannot clear constants.
参数属性
| 类型: | SwitchParameter |
| 默认值: | None |
| 支持通配符: | False |
| 不显示: | False |
参数集
(All)
| Position: | Named |
| 必需: | False |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | False |
| 来自剩余参数的值: | 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.
参数属性
| 类型: | String[] |
| 默认值: | None |
| 支持通配符: | True |
| 不显示: | False |
参数集
(All)
| Position: | Named |
| 必需: | False |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | False |
| 来自剩余参数的值: | False |
-Name
Specifies the name of the variable to be cleared. Wildcards are permitted. This parameter is required, but the parameter name ("Name") is optional.
参数属性
| 类型: | String[] |
| 默认值: | None |
| 支持通配符: | True |
| 不显示: | False |
参数集
(All)
| Position: | 0 |
| 必需: | True |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | True |
| 来自剩余参数的值: | False |
-PassThru
Returns an object representing the item with which you are working. By default, this cmdlet does not generate any output.
参数属性
| 类型: | SwitchParameter |
| 默认值: | None |
| 支持通配符: | False |
| 不显示: | False |
参数集
(All)
| Position: | Named |
| 必需: | False |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | False |
| 来自剩余参数的值: | 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.
参数属性
| 类型: | String |
| 默认值: | None |
| 支持通配符: | False |
| 不显示: | False |
参数集
(All)
| Position: | Named |
| 必需: | False |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | False |
| 来自剩余参数的值: | False |
-WhatIf
Shows what would happen if the cmdlet runs. The cmdlet is not run.
参数属性
| 类型: | SwitchParameter |
| 默认值: | False |
| 支持通配符: | False |
| 不显示: | False |
| 别名: | wi |
参数集
(All)
| Position: | Named |
| 必需: | False |
| 来自管道的值: | False |
| 来自管道的值（按属性名称）: | False |
| 来自剩余参数的值: | False |
CommonParameters
This cmdlet supports the common parameters: -Debug, -ErrorAction, -ErrorVariable, -InformationAction, -InformationVariable, -OutBuffer, -OutVariable, -PipelineVariable, -ProgressAction, -Verbose, -WarningAction, and -WarningVariable. For more information, see about_CommonParameters.
输入
None
You cannot pipe objects to this cmdlet.
输出
None or System.Management.Automation.PSVariable
When you use the PassThru parameter, this cmdlet generates a System.Management.Automation.PSVariable object representing the cleared variable. Otherwise, this cmdlet does not generate any output.
备注
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.
You can also refer to Clear-Variable by its built-in alias, clv. For more information, see about_Aliases.