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WhatIf, Confirm, and ValidateOnly switches

 

Applies to: Exchange Server 2013

Topic Last Modified: 2012-10-04

Both experienced administrators and script writers, and administrators who are new to Exchange and scripting, can benefit from using the WhatIf, Confirm, and ValidateOnly switches. These switches let you control how your commands run and indicate exactly what a command will do before it affects data. This functionality is quite valuable as you transition from your test environment into your production environment and as you roll out new scripts or commands.

The WhatIf, Confirm, and ValidateOnly switches are especially useful when you use them with commands that modify objects that are returned by using a filter or by using a Get command in a pipeline. This topic describes each switch and also provides an example command for each switch.

importantImportant:
If you want to use the WhatIf, Confirm, and ValidateOnly switches with commands in a script, you must add the appropriate switch to each command in the script, and not on the command line that calls the script.
noteNote:
WhatIf, Confirm, and ValidateOnly are called switch parameters. For more information about switch parameters, see Parameters.

The WhatIf switch instructs the command to which it is applied to run but only to display the objects that would be affected by running the command and what changes would be made to those objects. The switch does not actually change any of those objects. When you use the WhatIf switch, you can see whether the changes that would be made to those objects match your expectations, without the worry of modifying those objects.

When you run a command together with the WhatIf switch, you put the WhatIf switch at the end of the command, as in the following example:

New-AcceptedDomain -Name "Contoso Domain" -DomainName "contoso.com" -WhatIf 

When you run this example command, the following text is returned by the Shell:

What if: Creating Accepted Domain "Contoso Domain" with domain name "contoso.com".

The Confirm switch instructs the command to which it is applied to stop processing before any changes are made. The command then prompts you to acknowledge each action before it continues. When you use the Confirm switch, you can step through changes to objects to make sure that changes are made only to the specific objects that you want to change. This functionality is useful when you apply changes to many objects and want precise control over the operation of the Shell. A confirmation prompt is displayed for each object before the Shell modifies the object.

By default, the Shell automatically applies the Confirm switch to cmdlets that have the following verbs:

  • Clear
  • Disable
  • Dismount
  • Move
  • Remove
  • Stop
  • Suspend
  • Uninstall

When a cmdlet runs that has any of these verbs, the Shell automatically stops the command and waits for your acknowledgement before it continues to process.

If you want to manually apply the Confirm switch to a command, include the Confirm switch at the end of the command, as in the following example:

Get-JournalRule | Enable-JournalRule -Confirm

When you run this example command, the following confirmation prompt is returned by the Shell:

Confirm
Are you sure you want to perform this action?
Enabling journal rule "Litigation Journal Rule".
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help
(default is "Y"):

The confirmation prompt gives you the following choices:

  • [Y] Yes   Type Y to instruct the command to continue the operation. The next operation will present another confirmation prompt. [Y] Yes is the default choice.
  • [A] Yes to All   Type A to instruct the command to continue the operation and all subsequent operations. You will not receive additional confirmation prompts for the duration of this command.
  • [N] No   Type N to instruct the command to skip this operation and continue with the next operation. The next operation will present another confirmation prompt.
  • [L] No to All   Type L to instruct the command to skip this operation and all subsequent operations.
  • [S] Suspend   Type S to pause the current pipeline and return to the command line. Type Exit to resume the pipeline.
  • [?] Help   Type ? to display confirmation prompt Help on the command line.

If you want to override the default behavior of the Shell and suppress the confirmation prompt for cmdlets on which it is automatically applied, you can include the Confirm switch with a value of $False, as in the following example:

Get-JournalRule | Disable-JournalRule -Confirm:$False

In this case, no confirmation prompt is displayed.

CautionCaution:
The default value of the Confirm switch is $True. The default behavior of the Shell is to automatically display a confirmation prompt. If you suppress this default behavior, you instruct the command to suppress all confirmation prompts for the duration of that command. The command will process all objects that meet the criteria for the command without confirmation.

The ValidateOnly switch instructs the command to which it is applied to evaluate all the conditions and requirements that are needed to perform the operation before you apply any changes. The ValidateOnly switch is available on cmdlets that may take a long time to run, have several dependencies on multiple systems, or affect critical data, such as mailboxes.

When you apply the ValidateOnly switch to a command, the command runs through the whole process. The command performs each action as it would without the ValidateOnly switch. But the command doesn't change any objects. When the command completes its process, it displays a summary with the results of the validation. If the validation indicates that the command was successful, you can run the command again without the ValidateOnly switch.

When you run a command together with the ValidateOnly switch, you put the ValidateOnly switch at the end of the command.

 
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