about_CommonParameters

简短说明

Describes the parameters that can be used with any cmdlet.

详细说明

The common parameters are a set of cmdlet parameters that you can use with any cmdlet. They're implemented by PowerShell, not by the cmdlet developer, and they're automatically available to any cmdlet.

You can use the common parameters with any cmdlet, but they might not have an effect on all cmdlets. 例如，如果 cmdlet 不生成任何详细输出，则使用 Verbose 公共参数不起作用。

The common parameters are also available on advanced functions that use the CmdletBinding attribute or the Parameter attribute.

Several common parameters override system defaults or preferences that you set using the PowerShell preference variables. Unlike the preference variables, the common parameters affect only the commands in which they're used.

For more information, see about_Preference_Variables.

The following list displays the common parameters. Their aliases are listed in parentheses.

• Debug (db)
• ErrorAction (ea)
• ErrorVariable (ev)
• InformationAction (infa)
• InformationVariable (iv)
• OutVariable (ov)
• OutBuffer (ob)
• PipelineVariable (pv)
• Verbose (vb)
• WarningAction (wa)
• WarningVariable (wv)

The Action parameters are ActionPreference type values. ActionPreference is an enumeration with the following values:

名字	价值
Break	6
Suspend	5
Ignore	4
Inquire	3
Continue	2
Stop	1
SilentlyContinue	0

You may use the name or the value with the parameter.

In addition to the common parameters, many cmdlets offer risk mitigation parameters. Cmdlets that involve risk to the system or to user data usually offer these parameters.

The risk mitigation parameters are:

• WhatIf (wi)
• Confirm (cf)

Common parameter descriptions

-Debug

Displays programmer-level detail about the operation done by the command. This parameter works only when the command generates a debugging message. For example, this parameter works when a command contains the Write-Debug cmdlet.

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

By default, debugging messages aren't displayed because the value of the $DebugPreference variable is SilentlyContinue.

The Debug parameter overrides the value of the $DebugPreference variable for the current command, setting the value of $DebugPreference to Continue.

-Debug:$true has the same effect as -Debug. Use -Debug:$false to suppress the display of debugging messages when $DebugPreference isn't SilentlyContinue, which is the default.

-ErrorAction

Determines how the cmdlet responds to a non-terminating error from the command. This parameter works only when the command generates a non-terminating error, such as those from the Write-Error cmdlet.

Type: ActionPreference
Aliases: ea
Accepted values: Break, Suspend, Ignore, Inquire, Continue, Stop, SilentlyContinue
Required: False
Position: Named
Default value: Depends on preference variable
Accept pipeline input: False
Accept wildcard characters: False

The ErrorAction parameter overrides the value of the $ErrorActionPreference variable for the current command. Because the default value of the $ErrorActionPreference variable is Continue, error messages are displayed and execution continues unless you use the ErrorAction parameter.

The ErrorAction parameter has no effect on terminating errors (such as missing data, parameters that aren't valid, or insufficient permissions) that prevent a command from completing successfully.

• Break Enters the debugger when an error occurs or an exception is raised.
• Continue displays the error message and continues executing the command. Continue 为默认值。
• Ignore suppresses the error message and continues executing the command. Unlike SilentlyContinue, Ignore doesn't add the error message to the $Error automatic variable. The Ignore value is introduced in PowerShell 3.0.
• Inquire displays the error message and prompts you for confirmation before continuing execution. This value is rarely used.
• SilentlyContinue suppresses the error message and continues executing the command.
• Stop displays the error message and stops executing the command.
• Suspend is only available for workflows which aren't supported in PowerShell 6 and beyond.

注释

The ErrorAction parameter overrides, but doesn't replace the value of the $ErrorActionPreference variable when the parameter is used in a command to run a script or function.

-ErrorVariable

Error records are automatically store in the $Error automatic variable. 有关详细信息，请参阅 about_Automatic_Variables。

When you use the ErrorVariable parameter on a command, PowerShell also stores the error records emitted by the command in the variable specified by the parameter.

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

By default, new error messages overwrite error messages that are already stored in the variable. To append the error message to the variable content, put a plus sign (+) before the variable name.

For example, the following command creates the $a variable and then stores any errors in it:

Get-Process -Id 6 -ErrorVariable a

The following command adds any error messages to the $a variable:

Get-Process -Id 2 -ErrorVariable +a

The following command displays the contents of $a:

$a

You can use this parameter to create a variable that contains only error messages from specific commands and doesn't affect the behavior of the $Error automatic variable. The $Error automatic variable contains error messages from all the commands in the session. You can use array notation, such as $a[0] or $error[1,2] to refer to specific errors stored in the variables.

注释

The custom error variable contains all errors generated by the command, including errors from calls to nested functions or scripts.

-InformationAction

Introduced in PowerShell 5.0. Within the command or script in which it's used, the InformationAction common parameter overrides the value of the $InformationPreference preference variable, which by default is set to SilentlyContinue. When you use Write-Information in a script with InformationAction, Write-Information values are shown depending on the value of the InformationAction parameter. 有关 $InformationPreference的详细信息，请参阅 about_Preference_Variables。

Type: ActionPreference
Aliases: infa
Accepted values: Break, Suspend, Ignore, Inquire, Continue, Stop, SilentlyContinue
Required: False
Position: Named
Default value: Depends on preference variable
Accept pipeline input: False
Accept wildcard characters: False

• Break Enters the debugger at an occurrence of the Write-Information command.
• Stop stops a command or script at an occurrence of the Write-Information command.
• Ignore suppresses the informational message and continues running the command. Unlike SilentlyContinue, Ignore completely forgets the informational message; it doesn't add the informational message to the information stream.
• Inquire displays the informational message that you specify in a Write-Information command, then asks whether you want to continue.
• Continue displays the informational message, and continues running.
• Suspend isn't supported on PowerShell 6 and higher as it is only available for workflows.
• SilentlyContinue no effect as the informational message aren't (Default) displayed, and the script continues without interruption.

注释

The InformationAction parameter overrides, but doesn't replace the value of the $InformationAction preference variable when the parameter is used in a command to run a script or function.

-InformationVariable

Introduced in PowerShell 5.0. When you use the InformationVariable common parameter, information records are stored in a variable specified by the parameter. And PowerShell cmdlet can write information records to the Information stream. You can also use the Write-Information cmdlet to write information records.

Information records are displayed as messages in the console by default. You can control the display of information record by using the InformationAction common parameter. You can also change the behavior using the $InformationPreference preference variable. 有关 $InformationPreference的详细信息，请参阅 about_Preference_Variables。

注释

The information variable contains all information messages generated by the command, including information messages from calls to nested functions or scripts.

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

By default, new information record overwrite values that are already stored in the variable. To append the error message to the variable content, put a plus sign (+) before the variable name.

-OutBuffer

Determines the number of objects to accumulate in a buffer before any objects are sent through the pipeline. If you omit this parameter, objects are sent as they're generated.

Type: Int32
Aliases: ob
Required: False
Position: Named
Default value: None
Accept pipeline input: False
Accept wildcard characters: False

This resource management parameter is designed for advanced users. When you use this parameter, PowerShell sends data to the next cmdlet in batches of OutBuffer + 1.

The following example alternates displays between to ForEach-Object process blocks that use the Write-Host cmdlet. The display alternates in batches of 2 or OutBuffer + 1.

1..4 | ForEach-Object {
        Write-Host "$($_): First"; $_
      } -OutBuffer 1 | ForEach-Object {
                        Write-Host "$($_): Second" }

1: First
2: First
1: Second
2: Second
3: First
4: First
3: Second
4: Second

-OutVariable

Stores output objects from the command in the specified variable in addition to sending the output along the pipeline.

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

To add the output to the variable, instead of replacing any output that might already be stored there, type a plus sign (+) before the variable name.

For example, the following command creates the $out variable and stores the process object in it:

Get-Process PowerShell -OutVariable out

The following command adds the process object to the $out variable:

Get-Process iexplore -OutVariable +out

The following command displays the contents of the $out variable:

$out

注释

The variable created by the OutVariable parameter is a [System.Collections.ArrayList].

-PipelineVariable

PipelineVariable allows access to the most recent value passed into the next pipeline segment by the command that uses this parameter. Any command in the pipeline can access the value using the named PipelineVariable. The value is assigned to the variable when it's passed into the next pipeline segment. This makes the PipelineVariable easier to use than a specific temporary variable, which might need to be assigned in multiple locations.

Unlike $_ or $PSItem, using a PipelineVariable allows any pipeline command to access pipeline values passed (and saved) by commands other than the immediately preceding command. Pipeline commands can access the last value piped from while processing the next item passing through the pipeline. This allows a command to feed back its output to a previous command (or itself).

注释

Advanced functions can have up to three script blocks: begin, process, and end. When using the PipelineVariable parameter with advanced functions, only values from the first defined script block are assigned to the variable as the function runs. For more information, see Advanced functions. PowerShell 7.2 corrects this behavior.

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

Valid values are strings, the same as for any variable names.

谨慎

The PipelineVariable is scoped to the pipeline in which it's invoked. Variables outside the pipeline, which use same name, are cleared before the pipeline is executed. The PipelineVariable goes out of scope when the pipeline terminates. If multiple commands within the pipeline specify the same PipelineVariable then there is only one shared variable. That variable is updated with the most recent piped output from the command that specifies the variable.

Some blocking commands collect all the pipeline items before producing any output, for example Sort-Object or Select-Object -Last. Any PipelineVariable assigned in a command before such a blocking command always contains the final piped item from the preceding command when used in a command after the blocking command.

The following is an example of how PipelineVariable works. In this example, the PipelineVariable parameter is added to a Foreach-Object command to store the results of the command in variables. A range of numbers, 1 to 5, are piped into the first Foreach-Object command, the results of which are stored in a variable named $temp.

The results of the first Foreach-Object command are piped into a second Foreach-Object command, which displays the current values of $temp and $_.

# Create a variable named $temp
$temp=8
Get-Variable temp
# Note that the variable just created isn't available on the
# pipeline when -PipelineVariable creates the same variable name
1..5 | ForEach-Object -PipelineVariable temp -Begin {
    Write-Host "Step1[BEGIN]:`$temp=$temp"
} -Process {
  Write-Host "Step1[PROCESS]:`$temp=$temp - `$_=$_"
  Write-Output $_
} | ForEach-Object {
  Write-Host "`tStep2[PROCESS]:`$temp=$temp - `$_=$_"
}
# The $temp variable is deleted when the pipeline finishes
Get-Variable temp

Name                           Value
----                           -----
temp                           8

Step1[BEGIN]:$temp=
Step1[PROCESS]:$temp= - $_=1
        Step2[PROCESS]:$temp=1 - $_=1
Step1[PROCESS]:$temp=1 - $_=2
        Step2[PROCESS]:$temp=2 - $_=2
Step1[PROCESS]:$temp=2 - $_=3
        Step2[PROCESS]:$temp=3 - $_=3
Step1[PROCESS]:$temp=3 - $_=4
        Step2[PROCESS]:$temp=4 - $_=4
Step1[PROCESS]:$temp=4 - $_=5
        Step2[PROCESS]:$temp=5 - $_=5

Name                           Value
----                           -----
temp

-Verbose

Displays detailed information about the operation done by the command. This information resembles the information in a trace or in a transaction log. 仅当命令生成详细消息时，此参数才有效。 For example, this parameter works when a command contains the Write-Verbose cmdlet.

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

The Verbose parameter overrides the value of the $VerbosePreference variable for the current command. Because the default value of the $VerbosePreference variable is SilentlyContinue, verbose messages aren't displayed by default.

• -Verbose:$true has the same effect as -Verbose
• -Verbose:$false suppresses the display of verbose messages. Use this parameter when the value of $VerbosePreference isn't SilentlyContinue (the default).

-WarningAction

Determines how the cmdlet responds to a warning from the command. Continue is the default value. This parameter works only when the command generates a warning message. For example, this parameter works when a command contains the Write-Warning cmdlet.

Type: ActionPreference
Aliases: wa
Accepted values: Break, Suspend, Ignore, Inquire, Continue, Stop, SilentlyContinue
Required: False
Position: Named
Default value: Depends on preference variable
Accept pipeline input: False
Accept wildcard characters: False

The WarningAction parameter overrides the value of the $WarningPreference variable for the current command. Because the default value of the $WarningPreference variable is Continue, warnings are displayed and execution continues unless you use the WarningAction parameter.

• Break enters the debugger when a warning occurs.
• Continue displays the warning messages and continues executing the command. Continue 为默认值。
• Inquire displays the warning message and prompts you for confirmation before continuing execution. This value is rarely used.
• SilentlyContinue suppresses the warning message and continues executing the command.
• Stop displays the warning message and stops executing the command.

注释

The WarningAction parameter overrides, but doesn't replace the value of the $WarningAction preference variable when the parameter is used in a command to run a script or function.

-WarningVariable

Stores warning records about the command in the specified variable.

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

All generated warnings are saved in the variable even if the warnings aren't displayed to the user.

To append the warnings to the variable content, instead of replacing any warnings that might already be stored there, type a plus sign (+) before the variable name.

For example, the following command creates the $a variable and then stores any warnings in it:

Get-Process -Id 6 -WarningVariable a

The following command adds any warnings to the $a variable:

Get-Process -Id 2 -WarningVariable +a

The following command displays the contents of $a:

$a

You can use this parameter to create a variable that contains only warnings from specific commands. You can use array notation, such as $a[0] or $warning[1,2] to refer to specific warnings stored in the variable.

注释

The warning variable contains all warnings generated by the command, including warnings from calls to nested functions or scripts.

Risk Management Parameter Descriptions

-WhatIf

Displays a message that describes the effect of the command, instead of executing the command.

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

The WhatIf parameter overrides the value of the $WhatIfPreference variable for the current command. Because the default value of the $WhatIfPreference variable is 0 (disabled), WhatIf behavior isn't done without the WhatIf parameter. For more information, see about_Preference_Variables.

• $true has the same effect as -WhatIf.
• $false suppresses the automatic WhatIf behavior that results when the value of the $WhatIfPreference variable is 1.

For example, the following command uses the -WhatIf parameter in a Remove-Item command:

Remove-Item Date.csv -WhatIf

Instead of removing the item, PowerShell lists the operations it would do and the items that would be affected. 该命令会生成以下输出：

What if: Performing operation "Remove File" on
Target "C:\ps-test\date.csv".

-Confirm

Prompts you for confirmation before executing the command.

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

The Confirm parameter overrides the value of the $ConfirmPreference variable for the current command. 默认值为 true。 For more information, see about_Preference_Variables.

• $true has the same effect as -Confirm.
• $false suppresses automatic confirmation, which occurs when the value of $ConfirmPreference is less than or equal to the estimated risk of the cmdlet.

For example, the following command uses the Confirm parameter with a Remove-Item command. Before removing the item, PowerShell lists the operations it would do and the items that would be affected, and asks for approval.

PS C:\ps-test> Remove-Item tmp*.txt -Confirm

Confirm
Are you sure you want to perform this action?
Performing operation "Remove File" on Target " C:\ps-test\tmp1.txt
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend
[?] Help (default is "Y"):

The Confirm response options are as follows:

响应	结果
Yes (Y)	Perform the action.
Yes to All (A)	Perform all actions and suppress subsequent Confirm
	queries for this command.
No (N):	Don't perform the action.
No to All (L):	Don't perform any actions and suppress subsequent
	Confirm queries for this command.
Suspend (S):	Pause the command and create a temporary session.
Help (?)	Display help for these options.

The Suspend option places the command on hold and creates a temporary nested session in which you can work until you're ready to choose a Confirm option. The command prompt for the nested session has two extra carets (>>) to indicate that it's a child operation of the original parent command. You can run commands and scripts in the nested session. To end the nested session and return to the Confirm options for the original command, type "exit".

In the following example, the Suspend option (S) is used to halt a command temporarily while the user checks the help for a command parameter. After obtaining the needed information, the user types "exit" to end the nested prompt and then selects the Yes (y) response to the Confirm query.

PS C:\ps-test> New-Item -ItemType File -Name Test.txt -Confirm

Confirm
Are you sure you want to perform this action?

Performing operation "Create File" on Target "Destination:
C:\ps-test\test.txt".
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default
is "Y"): s

PS C:\ps-test> Get-Help New-Item -Parameter ItemType

-ItemType <string>
Specifies the provider-specified type of the new item.

Required?                    false
Position?                    named
Default value
Accept pipeline input?       true (ByPropertyName)
Accept wildcard characters?  false

PS C:\ps-test> exit

Confirm
Are you sure you want to perform this action?
Performing operation "Create File" on Target "Destination: C:\ps-test\test
.txt".
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help (defau
lt is "Y"): y

Directory: C:\ps-test

Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---         8/27/2010   2:41 PM          0 test.txt

另请参阅

• about_Preference_Variables
• Write-Debug
• Write-Error
• Write-Verbose
• Write-Warning