TOPIC
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 are implemented by Windows PowerShell, not
by the cmdlet developer, and they are 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 does not
generate any verbose output, using the Verbose common parameter
has no effect.
Several common parameters override system defaults or preferences
that you set by using the Windows PowerShell preference variables. Unlike
the preference variables, the common parameters affect only the commands
in which they are 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 common parameters are:
-Verbose
-Debug
-WarningAction
-WarningVariable
-ErrorAction
-ErrorVariable
-OutVariable
-OutBuffer
The risk mitigation parameters are:
-WhatIf
-Confirm
For more information about preference variables, type:
help about_preference_variables
Common Parameter Descriptions
-Verbose[:{$true | $false}]
Displays detailed information about the operation performed 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
are not displayed by default.
Valid values:
$true (-Verbose:$true) has the same effect as -Verbose.
$false (-Verbose:$false) suppresses the display of verbose
messages. Use this parameter when the value of $VerbosePreference
is not SilentlyContinue (the default).
-Debug[:{$true | $false}]
Displays programmer-level detail about the operation performed 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. Because the default value of the
$DebugPreference variable is SilentlyContinue, debugging messages
are not displayed by default.
Valid values:
$true (-Debug:$true). Has the same effect as -Debug.
$false (-Debug:$false). Suppresses the display of debugging
messages when the value of the $DebugPreference is not
SilentlyContinue (the default).
-WarningAction[:{SilentlyContinue | Continue | Inquire | Stop}]
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.
Valid Values:
SilentlyContinue. Suppresses the warning message and continues
executing the command.
Continue. Displays the warning message and continues executing
the command. "Continue" is the default value.
Inquire. Displays the warning message and prompts you for
confirmation before continuing execution. This value is rarely
used.
Stop. Displays the warning message and stops executing the
command.
-WarningVariable [+]<variable-name>
Stores warnings about the command in the specified variable.
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.
-ErrorAction[:{SilentlyContinue | Continue | Inquire | Stop)]
Determines how the cmdlet responds to a non-terminating error
from the command. This parameter works only when the command generates
a debugging message. For example, this parameters works when a command
contains 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 are not valid, or insufficient
permissions) that prevent a command from completing successfully.
Valid values:
SilentlyContinue. Suppresses the error message and continues
executing the command.
Continue. Displays the error message and continues executing
the command. "Continue" is the default value.
Inquire. Displays the error message and prompts you for
confirmation before continuing execution. This value is rarely
used.
Stop. Displays the error message and stops executing the
command.
-ErrorVariable [+]<variable-name>
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.
-OutVariable [+]<variable-name>
Stores output objects from the command in the specified variable and
displays it at the command line.
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:
$out
-OutBuffer <Int32>
Determines the number of objects to accumulate in a buffer before
any objects are sent through the pipeline. If you omit this parameter,
objects are sent as they are generated.
This resource management parameter is designed for advanced users.
When you use this parameter, Windows PowerShell does not call the
next cmdlet in the pipeline until the number of objects generated
equals OutBuffer + 1. Thereafter, it sends all objects as they are
generated.
Risk Management Parameter Descriptions
-WhatIf[:{$true | $false}]
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 is not
performed without the WhatIf parameter. For more information, type
the following command:
get-help about_preference_variables
Valid values:
$true (-WhatIf:$true). Has the same effect as -WhatIf.
$false (-WhatIf:$false). Suppresses the automatic WhatIf behavior
that results when the value of the $WhatIfPreference variable
is 1.
For example, the following command uses the WhatIf parameter in a
Remove-Item command:
PS> remove-item date.csv -whatif
Instead of removing the item, Windows PowerShell lists the operations
it would perform and the items that would be affected. This command
produces the following output:
What if: Performing operation "Remove File" on
Target "C:\ps-test\date.csv".
-Confirm[:{$true | $false}]
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 High. For more
information, type the following command:
get-help about_preference_variables
Valid values:
$true (-WhatIf:$true). Has the same effect as -Confirm.
$false(-Confirm:$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, Windows PowerShell
lists the operations it would perform and the items that would be
affected, and asks for approval.
PS C:\ps-test> remove-item tmp*.txt -confirm
This command produces the following output:
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"):
SEE ALSO
about_Preference_Variables
Write-Debug
Write-Warning
Write-Error
Write-Verbose