about_CommonParameters

Short description

Describes the parameters that can be used with any cmdlet.

Long description

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. For example, if a cmdlet doesn't generate any verbose output, using the Verbose common parameter has no effect.

The common parameters are also available on advanced functions that use the CmdletBinding attribute or the Parameter attribute. When you use these attributes, PowerShell automatically adds the Common Parameters. You can't create any parameters that use the same names as the Common Parameters.

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)
• ProgressAction (proga)
• Verbose (vb)
• WarningAction (wa)
• WarningVariable (wv)

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

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 parameters

-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 is the default.
• 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.

-ErrorVariable

Error records are automatically store in the $Error automatic variable. For more information, see 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.

-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. For more information about $InformationPreference, see 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.

-InformationVariable

Introduced in PowerShell 5.0. When you use the InformationVariable common parameter, information records are stored in the 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. For more information about $InformationPreference, see about_Preference_Variables.

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

-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).

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.

The following example illustrates how the PipelineVariable works. In this example, five numbers are piped into the first ForEach-Object command. Each item in the pipeline is stored in the pipeline variable named $Temp.

The Process block of the first ForEach-Object command pipes the pipeline item into the downstream ForEach-Object command. The state of the variables is displayed in each step.

# Create a variable named $Temp
$Temp = 8
Get-Variable Temp | Format-Table

$InformationPreference = 'Continue'
Write-Information '-------------------------------------------------'
111,222,333,444,555 | ForEach-Object -PipelineVariable Temp -Begin {

  # Note that the newly create $Temp variable doesn't contain the value 8
  # assigned before the pipeline started and that $PSItem is empty in
  # the Begin block.
  Write-Information "Upstream (Begin):   PSItem = '$PSItem', Temp = '$Temp'"

} -Process {

  Write-Information "Upstream (Process): PSItem = '$PSItem', Temp = '$Temp'"
  return $PSItem

} | ForEach-Object -Process {

  Write-Information "`tDownstream: PSItem = '$PSItem', Temp = '$Temp'"

}
Write-Information '-------------------------------------------------'

# The $Temp variable is deleted when the pipeline finishes
Get-Variable Temp | Format-Table

Name                           Value
----                           -----
Temp                           8

-------------------------------------------------
Upstream (Begin):   PSItem = '', Temp = ''
Upstream (Process): PSItem = '111', Temp = ''
        Downstream: PSItem = '111', Temp = '111'
Upstream (Process): PSItem = '222', Temp = '111'
        Downstream: PSItem = '222', Temp = '222'
Upstream (Process): PSItem = '333', Temp = '222'
        Downstream: PSItem = '333', Temp = '333'
Upstream (Process): PSItem = '444', Temp = '333'
        Downstream: PSItem = '444', Temp = '444'
Upstream (Process): PSItem = '555', Temp = '444'
        Downstream: PSItem = '555', Temp = '555'
-------------------------------------------------

Name                           Value
----                           -----
Temp

Issue 1: CDXML functions use [CmdletBinding()], which allows the PipelineVariable parameter.

Get-Partition -pv pvar

However, when you use PipelineVariable in Windows PowerShell v5.1, you receive the following error.

Get-Partition : Cannot retrieve the dynamic parameters for the cmdlet.
Object reference not set to an instance of an object.

At line:1 char:1
+ get-partition -PipelineVariable pvar
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [Get-Partition], ParameterBindingException
    + FullyQualifiedErrorId : GetDynamicParametersException,Get-Partition

Issue 2: When the preceding command is not a CDXML command and the downstream contains either command type, the PipelineVariable remains as the last accumulated object.

Get-CimInstance Win32_DiskDrive -pv pvar |
    ForEach-Object {
        Write-Host "Upstream: Disk $($pvar.Index)"
        return [pscustomobject]@{ DiskNumber = $_.Index }
    } | Get-Partition | ForEach-Object {
        Write-Host "Downstream: Disk $($pvar.Index)"
    }

Notice that the value of $pvar set to the last object in the pipeline for the second ForEach-Object command.

Upstream: Disk 1
Upstream: Disk 2
Upstream: Disk 0
Downstream: Disk 0
Downstream: Disk 0
Downstream: Disk 0
Downstream: Disk 0
Downstream: Disk 0
Downstream: Disk 0

-ProgressAction

Determines how PowerShell responds to progress updates generated by a script, cmdlet, or provider, such as the progress bars generated by the Write-Progress cmdlet. The Write-Progress cmdlet creates progress bars that show a command's status. The ProgressAction parameter was added in PowerShell 7.4.

The ProgressAction parameter takes one of the ActionPreference enumeration values: SilentlyContinue, Stop, Continue, Inquire, Ignore, Suspend, or Break.

The valid values are as follows:

• Break Enters the debugger at an occurrence of the Write-Progress command.
• Stop: Doesn't display the progress bar. Instead, it displays an error message and stops executing.
• Inquire: Doesn't display the progress bar. Prompts for permission to continue. If you reply with Y or A, it displays the progress bar.
• Continue: (Default) Displays the progress bar and continues with execution.
• SilentlyContinue: Executes the command, but doesn't display the progress bar.

Type: ActionPreference
Aliases: proga
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

-Verbose

Displays detailed information about the operation done by the command. This information resembles the information in a trace or in a transaction log. This parameter works only when the command generates a verbose message. 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 is the default.
• 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.

-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.

Risk management parameters

-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. This command produces the following output:

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. The default value is 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:

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

See also

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