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Write-Warning

Updated: April 21, 2010

Applies To: Windows PowerShell 2.0

Writes a warning message.

Syntax

Write-Warning [-Message] <string> [<CommonParameters>]

Description

The Write-Warning cmdlet writes a warning message to the Windows PowerShell host. The response to the warning depends on the value of the user's $WarningPreference variable and the use of the WarningAction common parameter.

Parameters

-Message <string>

Specifies the warning message.

 

Required?

true

Position?

1

Default Value

none

Accept Pipeline Input?

true (ByValue)

Accept Wildcard Characters?

false

<CommonParameters>

This command supports the common parameters: Verbose, Debug, ErrorAction, ErrorVariable, OutBuffer, OutVariable, WarningAction, and WarningVariable. For more information, see about_CommonParameters.

Inputs and Outputs

The input type is the type of the objects that you can pipe to the cmdlet. The return type is the type of the objects that the cmdlet returns.

 

Inputs

System.String

You can pipe a string that contains the warning to Write-Warning.

Outputs

None

Write-Warning writes only to the warning stream. It does not generate any other output.

Notes

The default value for the $WarningPreference variable is "Continue", which displays the warning and then continues executing the command. To determine valid values for a preference variable such as $WarningPreference, set it to a string of random characters, such as "abc". The resulting error message will list the valid values.

Example 1

C:\PS>write-warning "This is only a test warning."

Description

-----------

This command displays the message "WARNING: This is only a test warning."

Example 2

C:\PS>$w = "This is only a test warning."

C:\PS> $w | write-warning

Description

-----------

This example shows that you can use a pipeline operator (|) to send a string to Write-Warning. You can save the string in a variable, as shown in this command, or pipe the string directly to Write-Warning.

Example 3

C:\PS>$warningpreference

Continue

C:\PS> write-warning "This is only a test warning."
This is only a test warning.

C:\PS> $warningpreference = "SilentlyContinue"

C:\PS> write-warning "This is only a test warning."
C:\PS>

C:\PS> $warningpreference = "Stop"

C:\PS> write-warning "This is only a test warning."
WARNING: This is only a test message.
Write-Warning : Command execution stopped because the shell variable "WarningPreference" is set to Stop.
At line:1 char:14
+ write-warning <<<<  "This is only a test message."

Description

-----------

This example shows the effect of the value of the $WarningPreference variable on a Write-Warning command.

The first command displays the default value of the $WarningPreference variable, which is "Continue". As a result, when you write a warning, the warning message is displayed and execution continues.

When you change the value of the $WarningPreference variable, the effect of the Write-Warning command changes again. A value of "SilentlyContinue" suppresses the warning. A value of "Stop" displays the warning and then stops execution of the command.

For more information about the $WarningPreference variable, see about_Preference_Variables.

Example 4

C:\PS>write-warning "This is only a test warning." -warningaction Inquire

WARNING: This is only a test warning.

Confirm
Continue with this operation?
[Y] Yes  [A] Yes to All  [H] Halt Command  [S] Suspend  [?] Help (default is "Y"):

Description

-----------

This example shows the effect of the WarningAction common parameter on a Write-Warning command. You can use the WarningAction common parameter with any cmdlet to determine how Windows PowerShell responds to warnings resulting from that command. The WarningAction common parameter overrides the value of the $WarningPreference only for that particular command.

This command uses the Write-Warning cmdlet to display a warning. The WarningAction common parameter with a value of "Inquire" directs the system to prompt the user when the command displays a warning.

For more information about the WarningAction common parameter, see about_CommonParameters.

See Also

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