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, and on all workflows.
Several common parameters override system defaults or preferences that you set by using the PowerShell preference variables. Unlike the preference variables, the common parameters affect only the commands in which they're used.
In addition to the common parameters, many cmdlets offer the WhatIf and Confirm risk mitigation parameters. Cmdlets that involve risk to the system or to user data usually offer these parameters.
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 risk mitigation parameters are:
- WhatIf (wi)
- Confirm (cf)
For more information, see about_Preference_Variables.
COMMON PARAMETER DESCRIPTIONS
Debug
The alias for Debug is db.
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.
The Debug parameter overrides the value of the $DebugPreference variable
for the current command, setting the value of $DebugPreference to
Continue. Because the default value of the $DebugPreference variable is
SilentlyContinue, debugging messages aren't displayed by default.
-Debug:$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
The alias for ErrorAction is ea.
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.
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.
-ErrorAction:Continue display the error message and continues executing the
command. Continue is the default.
-ErrorAction: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.
-ErrorAction:Inquire displays the error message and prompts you for
confirmation before continuing execution. This value is rarely used.
-ErrorAction:SilentlyContinue suppresses the error message and continues
executing the command.
-ErrorAction:Stop displays the error message and stops executing the command.
-ErrorAction:Suspend isn't supported on PowerShell Core as it is only
available for workflows.
Note
The ErrorAction parameter overrides, but does not replace the value of
the $ErrorAction preference variable when the parameter is used in a
command to run a script or function.
ErrorVariable
The alias for ErrorVariable is ev.
ErrorVariable stores error messages about the command in the specified
variable and in the $Error automatic variable. For more information, type
the following command:
Get-Help about_Automatic_Variables
By default, new error messages overwrite error messages that are already stored
in the variable. To append the error message to the variable content, type 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. 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
The alias for InformationAction is ia.
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.
-InformationAction:Stop stops a command or script at an occurrence of the
Write-Information command.
-InformationAction: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.
-InformationAction:Inquire displays the informational message that you specify
in a Write-Information command, then asks whether you want to continue.
-InformationAction:Continue displays the informational message, and continues
running.
-InformationAction:Suspend isn't supported on PowerShell Core as it is only
available for workflows.
-InformationAction:SilentlyContinue no effect as the informational message
aren't (Default) displayed, and the script continues without interruption.
Note
The InformationAction parameter overrides, but does not replace the
value of the $InformationAction preference variable when the parameter
is used in a command to run a script or function.
InformationVariable
The alias for InformationVariable is iv.
Introduced in PowerShell 5.0. Within the command or script in which it's used,
the InformationVariable common parameter stores in a variable a string that
you specify by adding the Write-Information command. Write-Information
values are shown depending on the value of the InformationAction common
parameter; if you don't add the InformationAction common parameter,
Write-Information strings are shown depending on the value of the
$InformationPreference preference variable. For more information about
$InformationPreference, see about_Preference_Variables.
OutBuffer
The alias for OutBuffer is ob and takes a System.Int32 value.
Determines the number of objects to accumulate in a buffer before any objects are sent through the pipeline. If you omit this parameter, objects are sent as they're generated.
This resource management parameter is designed for advanced users. When you use
this parameter, PowerShell sends data to the next cmdlet in batches of
OutBuffer + 1.
The following example alternates displays between to ForEach-Object process
blocks that use the Write-Host cmdlet. The display alternates in batches of
2 or OutBuffer + 1.
1..4 | ForEach-Object {
Write-Host "$($_): 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
The alias for OutVariable is ov.
Stores output objects from the command in the specified variable in addition to sending the output along the pipeline.
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
Note
The variable created by the OutVariable parameter is a
[System.Collections.ArrayList].
PipelineVariable
The alias for PipelineVariable is pv and takes a string value.
PipelineVariable stores the value of the current pipeline element as a variable, for any named command as it flows through the pipeline.
Valid values are strings, the same as for any variable names.
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 10, are
piped into the first Foreach-Object command, the results of which are stored
in a variable named Left.
The results of the first Foreach-Object command are piped into a second
Foreach-Object command, which filters the objects returned by the first
Foreach-Object command. The results of the second command are stored in a
variable named Right.
In the third Foreach-Object command, the results of the first two
Foreach-Object piped commands, represented by the variables Left and
Right, are processed by using a multiplication operator. The command instructs
objects stored in the Left and Right variables to be multiplied, and
specifies that the results should be displayed as "Left range member * Right
range member = product".
1..10 | Foreach-Object -PipelineVariable Left -Process { $_ } |
Foreach-Object -PV Right -Process { 1..10 } |
Foreach-Object -Process { "$Left * $Right = " + ($Left*$Right) }
1 * 1 = 1
1 * 2 = 2
1 * 3 = 3
1 * 4 = 4
1 * 5 = 5
...
Verbose
The alias for Verbose is vb.
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.
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
The alias for WarningAction is wa.
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.
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.
-WarningAction:Continue displays the warning messages and continues executing
the command. Continue is the default.
-WarningAction:Inquire displays the warning message and prompts you for
confirmation before continuing execution. This value is rarely used.
-WarningAction:SilentlyContinue suppresses the warning message and continues
executing the command.
-WarningAction:Stop displays the warning message and stops executing the
command.
Note
The WarningAction parameter overrides, but does not replace the value of
the $WarningAction preference variable when the parameter is used in a
command to run a script or function.
WarningVariable
The alias for WarningVariable is wv.
Stores warnings about the command in the specified variable.
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.
Note
The WarningVariable parameter does not capture warnings from nested calls in functions or scripts.
Risk Management Parameter Descriptions
WhatIf
The alias for WhatIf is wi.
Displays a message that describes the effect of the command, instead of executing the command.
The WhatIf parameter overrides the value of the $WhatIfPreference variable
for the current command. Because the default value of the $WhatIfPreference
variable is 0 (disabled), WhatIf behavior isn't done without the
WhatIf parameter. For more information, type the following command:
Get-Help about_Preference_Variables
-WhatIf:$true has the same effect as -WhatIf.
-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
The alias for Confirm is cf.
Prompts you for confirmation before executing the command.
The Confirm parameter overrides the value of the $ConfirmPreference
variable for the current command. The default value is true. For more
information, type the following command:
Get-Help about_Preference_Variables
-Confirm:$true has the same effect as -Confirm.
-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:
| Response | Result |
|---|---|
| Yes (Y) | Perform the action. |
| Yes to All (A) | Perform all actions and suppress subsequent Confirm queries |
| for this command. | |
| No (N): | Do not perform the action. |
| No to All (L): | Do not 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
KEYWORDS
about_Common_Parameters