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about_Preference_Variables

Updated: April 21, 2010

Applies To: Windows PowerShell 2.0

TOPIC
    Preference Variables

SHORT DESCRIPTION
    Variables that customize the behavior of Windows PowerShell 

LONG DESCRIPTION
    Windows PowerShell includes a set of variables that enable you to 
    customize its behavior. These "preference variables" work like the
    options in GUI-based systems.

    The preference variables affect the Windows PowerShell operating 
    environment and all commands run in the environment. In many cases,
    the cmdlets have parameters that you can use to override the preference
    behavior for a specific command.

    The following table lists the preference variables and their default 
    values.

    Variable                             Default Value
    --------                             -------------
    $ConfirmPreference                   High
    $DebugPreference                     SilentlyContinue
    $ErrorActionPreference               Continue
    $ErrorView                           NormalView
    $FormatEnumerationLimit              4
    $LogCommandHealthEvent               False (not logged)
    $LogCommandLifecycleEvent            False (not logged)
    $LogEngineHealthEvent                True (logged)
    $LogEngineLifecycleEvent             True (logged)
    $LogProviderLifecycleEvent           True (logged)
    $LogProviderHealthEvent              True (logged)
    $MaximumAliasCount                   4096
    $MaximumDriveCount                   4096
    $MaximumErrorCount                   256
    $MaximumFunctionCount                4096
    $MaximumHistoryCount                 64
    $MaximumVariableCount                4096
    $OFS                                 (Space character (" "))
    $OutputEncoding		         ASCIIEncoding object
    $ProgressPreference                  Continue
    $PSEmailServer                       (None)
    $PSSessionApplicationName            WSMAN
    $PSSessionConfigurationName          http://schemas.microsoft.com/powershell/microsoft.powershell 
    $PSSessionOption                     (See below)
    $VerbosePreference                   SilentlyContinue
    $WarningPreference                   Continue
    $WhatIfPreference                    0



    Windows Powershell also includes the following environment variables that
    store user preferences. For more information about these environment
    variables, see about_Environment_Variables.

    Variable                                         
    --------    
    PSExecutionPolicyPreference                     
    PSModulePath                        


WORKING WITH PREFERENCE VARIABLES
    This document describes each of the preference variables.

    To display the current value of a specific preference variable, type
    the name of the variable. In response, Windows PowerShell provides the
    value. For example, the following command displays the value of the 
    $ConfirmPreference variable.

        PS> $ConfirmPreference
        High

    To change the value of a variable, use an assignment statement. For
    example, the following statement assigns the value "Medium" to the 
    $ConfirmPreference variable.

        PS> $ConfirmPreference = "Medium"

    Like all variables, the values that you set are specific to the current
    Windows PowerShell session. To make them effective in all Windows 
    PowerShell session, add them to your Windows PowerShell profile. For
    more information, see about_Profiles.


WORKING REMOTELY
   When you run commands on a remote computer, the remote commands are subject
   only to the preferences set in the Windows PowerShell client on the remote
   computer. For example, when you run a remote command, the value of the
   $DebugPreference variable on remote computer determines how Windows
   PowerShell responds to debugging messages. 

   For more information about remote commands, see about_remote.



$ConfirmPreference
------------------
    Determines whether Windows PowerShell automatically prompts you for
    confirmation before running a cmdlet or function. 
        
    When the value of the $ConfirmPreference variable (High, Medium, Low) is
    less than or equal to the risk assigned to the cmdlet or function (High,
    Medium, Low), Windows PowerShell automatically prompts you for confirmation          
    before running the cmdlet or function.

    If the value of the $ConfirmPreference variable is None, Windows PowerShell
    never automatically prompts you before running a cmdlet or function.

    To change the confirming behavior for all cmdlets and functions in the
    session, change the value of the $ConfirmPreference variable. 

    To override the $ConfirmPreference for a single command, use the Confirm
    parameter of the cmdlet or function. To request confirmation, use -Confirm.
    To suppress confirmation, use -Confirm:$false
    

    
    Valid values of $ConfirmPreference:

		None:    Windows PowerShell does not prompt automatically.
                         To request confirmation of a particular command, use
                         the Confirm parameter of the cmdlet or function.

		Low:     Windows PowerShell prompts for confirmation before
                         running cmdlets or functions with a low, medium, or high
                         risk. 

		Medium:  Windows PowerShell prompts for confirmation before
                         running cmdlets or functions with a medium, or high
                         risk. 

		High:    Windows PowerShell prompts for confirmation before
                         running cmdlets or functions with a high risk.



    DETAILED EXPLANATION
        When the actions of a cmdlet or function significantly affect the system,
        such as those that delete data or use a significant amount of system
        resources, Windows PowerShell can automatically prompt you for confirmation 
        before performing the action. 

        For example,

	    PS> remove-item file.txt

            Confirm
            Are you sure you want to perform this action?
            Performing operation "Remove File" on Target "C:\file.txt".
            [Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help (default is "Y"):

        The estimate of the risk is an attribute of the cmdlet or function known
        as its "ConfirmImpact". Users cannot change it.

        Cmdlets and functions that might pose a risk to the system have a
        Confirm parameter that you can use to request or suppress confirmation
        for a single command.

	Because most cmdlets and functions use the default risk value (ConfirmImpact)
        of Medium, and the default value of $ConfirmPreference is High, automatic
        confirmation rarely occurs. However, you can activate automatic confirmation by 
        changing the value of $ConfirmPreference to Medium or Low. 


    EXAMPLES
      This example shows the effect of the default value of $ConfirmPreference.
      The High value only confirms high-risk cmdlets and functions. Since most
      cmdlets and functions are medium risk, they are not automatically confirmed.

          PS> $confirmpreference              #Get the current value of the
          High                                 variable
          
          PS> remove-item temp1.txt           #Delete a file
          PS>                                 #Deleted without confirmation

           
          PS> remove-item temp2.txt -confirm  #Use the Confirm parameter to
                                               request confirmation

          Confirm
          Are you sure you want to perform this action?
          Performing operation "Remove File" on Target "C:\temp2.txt".
          [Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help (default is "Y"):


       The following example shows the effect of changing the value of
       $ConfirmPreference to Medium. Because most cmdlets and function are 
       medium-risk, they are automatically confirmed. To suppress the 
       confirmation prompt for a single command, use the Confirm parameter
       with a value of $false 

            
          PS> $confirmpreference = "Medium"  #Change the value of $ConfirmPreference
          PS> remove-item temp2.txt          #Deleting a file triggers confirmation         
                                     
          Confirm
          Are you sure you want to perform this action?
          Performing operation "Remove File" on Target "C:\temp2.txt".
          [Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help (default is "Y"):
	

          PS> remove-item temp3.txt -confirm:$false   #Use Confirm parameter
                                                       to suppress confirmation
          PS>


$DebugPreference
------------------
	Determines how Windows PowerShell responds to debugging messages 
        generated by a script, cmdlet or provider, or by a Write-Debug
        command at the command line. 

        Some cmdlets display debugging messages, which are typically very
        technical messages designed for programmers and technical support
        professionals. By default, debugging messages are not displayed, 
        but you can display debugging messages by changing the value of 
        $DebugPreference.
        
        You can also use the Debug common parameter of a cmdlet to display
        or hide the debugging messages for a specific command. For more 
        information, type: "get-help about_commonparameters".

        Valid values:
	    Stop:               Displays the debug message and stops 
                                executing. Writes an error to the console.

     	    Inquire:            Displays the debug message and asks you
                                whether you want to continue.

            Continue:           Displays the debug message and continues
                                with execution.

            SilentlyContinue:   No effect. The debug message is not 
            (Default)           displayed and execution continues without
                                 interruption.
             

    EXAMPLES
    
    The following examples show the effect of changing the values of 
    $DebugPreference when a Write-Debug command is entered at the command
    line. The change affects all debugging messages, including those
    generated by cmdlets and scripts. The examples also show the use of the
    Debug common parameter, which displays or hides the debugging messages
    related to a single command.

    This example shows the effect of the default value, "SilentlyContinue."
    The debug message is not displayed and processing continues. The final 
    command uses the Debug parameter to override the preference for a single
    command.

        PS> $debugpreference                    # Get the current value of
        SilentlyContinue                          $DebugPreference

        PS> write-debug "Hello, World"
        PS>                                     # The debug message is not
                                                  displayed.

        PS> write-debug "Hello, World" -Debug   # Use the Debug parameter
        DEBUG: Hello, World                     # The debug message is
                                                  is requested.                                                                                                    displayed and confirmation
        Confirm
        Continue with this operation?
        [Y] Yes  [A] Yes to All  [H] Halt Command  [S] Suspend  [?] Help (default is "Y"):

   
    This example shows the effect of the "Continue" value. The final command
    uses the Debug parameter with a value of $false to suppress the message
    for a single command.

        PS> $debugpreference = "Continue"   # Change the value to "Continue"

        PS> write-debug "Hello, World"
        DEBUG: Hello, World                 # The debug message is displayed
        PS>                                   and processing continues.
                                           

        PS> write-debug "Hello, World" -Debug:$false   
                                            # Use the Debug parameter with
                                              false.
        PS>                                 # The debug message is not
                                              displayed.

        
    This example shows the effect of the "Stop" value. The final command
    uses the Debug parameter with a value of $false to suppress the message
    for a single command.

        PS> $debugpreference = "Stop"       #Change the value to "Stop"
        PS> write-debug "Hello, World"
        DEBUG: Hello, World
        Write-Debug : Command execution stopped because the shell variable "DebugPreference" is
        set to Stop.
        At line:1 char:12
        + write-debug  <<<< "Hello, World"

        PS> write-debug "Hello, World" -Debug:$false   
                                            # Use the Debug parameter with
                                              $false
        PS>                                 # The debug message is not 
                                              displayed and processing is
                                              not stopped.
      

    This example shows the effect of the "Inquire" value. The final command
    uses the Debug parameter with a value of $false to suppress the message
    for a single command.

        PS> $debugpreference = "Inquire"
        PS> write-debug "Hello, World"
        DEBUG: Hello, World

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

        PS> write-debug "Hello, World" -Debug:$false   
                                            # Use the Debug parameter with
                                              $false
        PS>                                 # The debug message is not
                                              displayed and processing
                                              continues without interruption.


$ErrorActionPreference
----------------------
	Determines how Windows PowerShell responds to a non-terminating
        error (an error that does not stop the cmdlet processing) at the
        command line or in a script, cmdlet, or provider, such as the
        errors generated by the Write-Error cmdlet. 

        You can also use the ErrorAction common parameter of a cmdlet to 
        override the preference for a specific command. For more
        information, type: "get-help about_commonparameters".


        Valid values:
	    Stop:               Displays the error message and stops
                                executing. 

     	    Inquire:            Displays the error message and asks you
                                whether you want to continue.

            Continue:           Displays the error message and continues
            (Default)           executing.

            SilentlyContinue:   No effect. The error message is not
                                displayed and execution continues without
                                interruption.


       Neither $ErrorActionPreference nor the ErrorAction common parameter
       affect how Windows PowerShell responds to terminating errors (those
       that stop cmdlet processing).

       For more information about the ErrorAction common parameter, type
       "get-help about_commonparameters".


    EXAMPLES

    These examples show the effect of the different values of
    $ErrorActionPreference and the use of the ErrorAction common parameter
    to override the preference for a single command. The ErrorAction 
    parameter has the same valid values as the $ErrorActionPreference
    variable.
    
    This example shows the effect of the Continue value, which is the
    default.

        PS> $erroractionpreference                      
        Continue		# Display the value of the preference.		          
                                  
        PS> write-error "Hello, World"                  
                                # Generate a non-terminating error.

        write-error "Hello, World" : Hello, World       
                                # The error message is displayed and
                                  execution continues.

        PS> write-error "Hello, World" -ErrorAction:SilentlyContinue
                                # Use the ErrorAction parameter with a 
                                  value of "SilentlyContinue".
        PS>                                             
                                # The error message is not displayed and
                                  execution continues.

    This example shows the effect of the SilentlyContinue value.

        PS> $ErrorActionPreference = "SilentlyContinue"
                                # Change the value of the preference.
        PS> write-error "Hello, World"                  
                                # Generate an error message.
        PS>                     
                                # Error message is suppressed.
        PS> write-error "Hello, World" -erroraction:continue
                                # Use the ErrorAction parameter with a
                                  value of "Continue".
        write-error "Hello, World" -erroraction:continue : Hello, World
                                # The error message is displayed and
                                  execution continues.

       
    This example shows the effect of a real error. In this case, the command
    gets a non-existent file, nofile.txt. The example also uses the
    ErrorAction common parameter to override the preference.

        PS> $erroractionpreference                      
        SilentlyContinue        # Display the value of the preference.     
                                

        PS> get-childitem -path nofile.txt
        PS>                     # Error message is suppressed.

        PS> $ErrorActionPreference = "Continue" 
                                # Change the value to Continue.

        PS> get-childitem -path nofile.txt
        Get-ChildItem : Cannot find path 'C:\nofile.txt' because it does not exist.
        At line:1 char:4
        + get-childitem  <<<< nofile.txt

        PS> get-childitem -path nofile.txt -erroraction SilentlyContinue
                                # Use the ErrorAction parameter
        PS>                     
                                # Error message is suppressed.
  
        PS> $ErrorActionPreference = "Inquire"          
                                # Change the value to Inquire.
        PS> get-childitem -path nofile.txt

        Confirm
        Cannot find path 'C:\nofile.txt' because it does not exist.
        [Y] Yes  [A] Yes to All  [H] Halt Command  [S] Suspend  [?] Help (default is "Y"): y
        
        Get-ChildItem : Cannot find path 'C:\nofile.txt' because it does not exist.
        At line:1 char:4
        + get-childitem  <<<< nofile.txt

        PS> $ErrorActionPreference = "Continue"                  
                                # Change the value to Continue.
        PS> Get-Childitem nofile.txt -erroraction "Inquire"      
                                # Use the ErrorAction parameter to override
                                  the preference value.

        Confirm
        Cannot find path 'C:\nofile.txt' because it does not exist.         
        [Y] Yes  [A] Yes to All  [H] Halt Command  [S] Suspend  [?] Help (default is "Y"):


$ErrorView
----------
        Determines the display format of error messages in Windows 
        PowerShell. 

        Valid values:
	    NormalView:         A detailed view designed for most users. 
            (default)           Consists of a description of the error, the
                                name of the object involved in the error,
                                and arrows (<<<<) that point to the words
                                in the command that caused the error.

     	    CategoryView:       A succinct, structured view designed for
                                production environments. The format is:
                                {Category}: ({TargetName}:{TargetType}):[{Activity}], {Reason}

        For more information about the fields in CategoryView, see 
        "ErrorCategoryInfo class" in the Windows PowerShell SDK.
        
    EXAMPLES

    These example show the effect of the ErrorView values.

    This example shows how an error appears when the value of $ErrorView is
    NormalView. In this case, the Get-ChildItem command is used to find a 
    non-existent file.

        PS> $ErrorView                         # Verify the value.
        NormalView

        PS> get-childitem nofile.txt           # Find a non-existent file.
        Get-ChildItem : Cannot find path 'C:\nofile.txt' because it does not exist.
        At line:1 char:14
        + get-childitem  <<<< nofile.txt

    This example shows how the same error appears when the value of 
    $ErrorView is CategoryView.

        PS> $ErrorView = "CategoryView"        # Change the value to 
                                                 CategoryView

        PS> get-childitem nofile.txt
        ObjectNotFound: (C:\nofile.txt:String) [Get-ChildItem], ItemNotFoundException

 
   This example demonstrates that the value of ErrorView only affects the
   error display; it does not change the structure of the error object that
   is stored in the $error automatic variable. For information about the $error 
   automatic variable, see about_automatic_variables.

   This command takes the ErrorRecord object associated with the most recent
   error in the error array (element 0) and formats all of the properties
   of the error object in a list.
           
        PS> $error[0] | format-list -property * -force

        Exception    : System.Management.Automation.ItemNotFoundException: Cannot find path
                       'C:\nofile.txt' because it does not exist.
                       at System.Management.Automation.SessionStateInternal.GetChildItems(String path,
                       Boolean recurse, CmdletProviderContext context)
                       at System.Management.Automation.ChildItemCmdletProviderIntrinsics.Get(String path,
                       Boolean recurse, CmdletProviderContext context)
                       at Microsoft.PowerShell.Commands.GetChildItemCommand.ProcessRecord()
        TargetObject          : C:\nofile.txt
        CategoryInfo          : ObjectNotFound: (C:\nofile.txt:String) [Get-ChildItem],
                                ItemNotFoundException
        FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand
        ErrorDetails          :
        InvocationInfo        : System.Management.Automation.InvocationInfo


$FormatEnumerationLimit
-----------------------
        Determines how many enumerated items are included in a display. This
        variable does not affect the underlying objects; just the display.
        When the value of $FormatEnumerationLimit is less than the number of
        enumerated items, Windows PowerShell adds an ellipsis (...) to
        indicate items not shown.

        Valid values: Integers (Int32)
        Default value: 4

    EXAMPLES

        This example shows how to use the $FormatEnumerationLimit variable
        to improve the display of enumerated items. 

        The command in this example generates a table that lists all of the
        services running on the computer in two groups; one for running
        services and one for stopped services. It uses a Get-Service
        command to get all of the services, and then send the results
        through the pipeline to the Group-Object cmdlet, which groups the
        results by the service status. 

        The resulting display is a table that lists the status in the Name 
        column and the processes with that status in the Group column. (To
        change the column labels, use a hash table. For more information,
        see the examples in "get-help format-table -examples".) 

        There are a maximum of 4 services listed in the Group column for
        each status. To increase the number of items listed, increase 
        the value of $FormatEnumerationLimit to 1000.

        In the resulting display, the list in the Group column is now 
        limited by the line length. In the final command in the example, use
        the Wrap parameter of Format-Table to display all of the processes
        in each Status group.
         

        PS> $formatenumerationlimit         # Find the current value
        4
        
        PS> get-service | group-object -property status           
                                            # List all services grouped by
                                              status

        Count Name                      Group
        ----- ----                      -----
           60 Running                   {AdtAgent, ALG, Ati HotKey Poller, AudioSrv...}   
           41 Stopped                   {Alerter, AppMgmt, aspnet_state, ATI Smart...}

                                           # The list is truncated after
                                             4 items.


        PS> $formatenumerationlimit = 1000
                                           # Increase the limit to 1000.
        
        PS> get-service | group-object -property status           
                                           # Repeat the command.

        Count Name     Group
        ----- ----     -----
           60 Running  {AdtAgent, ALG, Ati HotKey Poller, AudioSrv, BITS, CcmExec...
           41 Stopped  {Alerter, AppMgmt, aspnet_state, ATI Smart, Browser, CiSvc...


        PS> get-service | group-object -property status | format-table -wrap
                                           # Add the Wrap parameter.

        Count Name       Group
        ----- ----       -----
           60 Running    {AdtAgent, ALG, Ati HotKey Poller, AudioSrv, BITS, CcmExec, Client
                         for NFS, CryptSvc, DcomLaunch, Dhcp, dmserver, Dnscache, ERSvc,   
                         Eventlog, EventSystem, FwcAgent, helpsvc, HidServ, IISADMIN,    
                         InoRPC, InoRT, InoTask, lanmanserver, lanmanworkstation, LmHosts, 
                         MDM, Netlogon, Netman, Nla, NtLmSsp, PlugPlay, PolicyAgent,   
                         ProtectedStorage, RasMan, RemoteRegistry, RpcSs, SamSs, Schedule,
                         seclogon, SENS, SharedAccess, ShellHWDetection, SMT PSVC, Spooler,    
                         srservice, SSDPSRV, stisvc, TapiSrv, TermService, Themes, TrkWks,
                         UMWdf, W32Time, W3SVC, WebClient, winmgmt, wscsvc, wuauserv,
                         WZCSVC, zzInterix}

           41 Stopped    {Alerter, AppMgmt, aspnet_state, ATI Smart, Browser, CiSvc,
                         ClipSrv, clr_optimization_v2.0.50727_32, COMSysApp, CronService, 
                         dmadmin, FastUserSwitchingCompatibility, HTTPFilter, ImapiService,
                         Mapsvc, Messenger, mnmsrvc, MSDTC, MSIServer, msvsmon80, NetDDE, 
                         NetDDEdsdm, NtmsSvc, NVSvc, ose, RasAuto, RDSessMgr, RemoteAccess,    
                         RpcLocator, SCardSvr, SwPrv, SysmonLog, TlntSvr, upnphost, UPS, 
                         VSS, WmdmPmSN, Wmi, WmiApSrv, xmlprov}


$Log*Event
----------
        The Log*Event preference variables determine which types of events
        are written to the Windows PowerShell event log in Event Viewer. By
        default, only engine and provider events are logged, but you can use
        the Log*Event preference variables to customize your log, such as 
        logging events about commands.     

        The Log*Event preference variables are as follows:

            $LogCommandHealthEvent: Logs errors and exceptions in command initialization
                and processing. Default = $false (not logged).

            $LogCommandLifecycleEvent: 
                Logs the starting and stopping of commands and command pipelines
                and security exceptions in command discovery. Default = $false (not logged).

            $LogEngineHealthEvent: Logs errors and failures of sessions. Default = $true (logged).

            $LogEngineLifecycleEvent: Logs the opening and closing of sessions. 
                Default = $true (logged).

            $LogProviderHealthEvent: Logs provider errors, such as read and write errors,
                lookup errors, and invocation errors. Default = $true (logged).

            $LogProviderLifecycleEvent: Logs adding and removing of Windows PowerShell providers.
                Default = $true (logged). (For information about Windows PowerShell providers, type:
                "get-help about_provider".


        To enable a Log*Event, type the variable with a value of $true, for example:

            $LogCommandLifeCycleEvent

            - or -

            $LogCommandLifeCycleEvent = $true


        To disable an event type, type the variable with a value of $false, for example:

            $LogCommandLifeCycleEvent = $false

        The events that you enable are effective only for the current Windows PowerShell
        console. To apply the configuration to all consoles, save the variable settings
        in your Windows PowerShell profile.


$MaximumAliasCount
------------------
        Determines how many aliases are permitted in a Windows PowerShell
        session. The default value, 4096, should be sufficient for most
        uses, but you can adjust it to meet your needs.

        Valid values: 1024 - 32768 (Int32)
        Default: 4096
      
        To count the aliases on your system, type: 
		
		(get-alias).count

$MaximumDriveCount
------------------
        Determines how many Windows PowerShell drives are permitted in a
        given session. This includes file system drives and data stores that
        are exposed by Windows PowerShell providers and appear as drives, 
        such as the Alias: and HKLM: drives.

        Valid values: 1024 - 32768 (Int32)
        Default: 4096
      
        To count the aliases on your system, type: 
		
		(get-psdrive).count



$MaximumErrorCount
------------------
        Determines how many errors are saved in the error history
        for the session. 

        Valid values: 256 - 32768 (Int32)
        Default: 256

        Objects that represent each retained error are stored in the 
        $Error automatic variable. This variable contains an array of error
        record objects, one for each error. The most recent error is the
        first object in the array ($Error[0]).
      
        To count the errors on your system, use the Count property of
        the $Error array. Type:
		
		$Error.count

        To display a specific error, use array notation to display 
        the error. For example, to see the most recent error, type:

                $Error[0]

        To display the oldest retained error, type:

                $Error[($Error.Count -1]

        To display the properties of the ErrorRecord object, type:

                $Error[0] | format-list -property * -force

        In this command, the Force parameter overrides the special
        formatting of ErrorRecord objects and reverts to the conventional
        format.

        To delete all errors from the error history, use the Clear method
        of the error array.

               PS> $Error.count
               17
               PS> $Error.clear()
               PS>
               PS> $Error.count
               0

       To find all properties and methods of an error array, use the
       Get-Member cmdlet with its InputObject parameter. When you pipe a
       collection of objects to Get-Member, Get-Member displays the
       properties and methods of the objects in the collection. When you use
       the InputObject parameter of Get-Member, Get-Member displays the
       properties and methods of the collection.


$MaximumFunctionCount
------------------
        Determines how many functions are permitted in a given session. 

        Valid values: 1024 - 32768 (Int32)
        Default: 4096

        To see the functions in your session, use the Windows PowerShell
        Function: drive that is exposed by the Windows PowerShell Function
        provider. (For more information about the Function provider, type
        "get-help function").

        To list the functions in the current session, type:

            get-childitem function:

        To count the functions in the current session, type:

            (get-childitem function:).count


$MaximumHistoryCount
------------------
        Determines how many commands are saved in the command history
        for the current session. 

        Valid values: 1 - 32768 (Int32)
        Default: 64

        To determine the number of commands current saved in the command
        history, type:
 
            (get-history).count

        To see the command saved in your session history, use the 
        Get-History cmdlet. For more information, type: 
        "get-help about_history".



$MaximumVariableCount
------------------
        Determines how many variables are permitted in a given session, 
        including automatic variables, preference variables, and the
        variables that you create in commands and scripts. 

        Valid values: 1024 - 32768 (Int32)
        Default: 4096

        To see the variables in your session, use the Get-Variable cmdlet
        and the features of the Windows PowerShell Variable: drive and the
        Windows PowerShell Variable provider. For information about the 
        Variable provider, type "get-help variable".

        To find the current number of variables on the system, type:

            (get-variable).count



$OFS
----
        Output Field Separator. Specifies the character that separates the
        elements of an array when the array is converted to a string. 

        Valid values: Any string.
        Default: Space

        By default, the $OFS variable does not exist and the output file
        separator is a space, but you can add this variable and set it to 
        any string.

    EXAMPLES

    This example shows that a space is used to separate the values when an
    array is converted to a string. In this case, an array of integers is
    stored in a variable and then the variable is cast as a string.

       PS> $array = 1,2,3                 # Store an array of integers.       

       PS> [string]$array                 # Cast the array to a string.
       1 2 3                              # Spaces separate the elements


    To change the separator, add the $OFS variable by assigning a value
    to it. To work correctly, the variable must be named $OFS.  

       PS> $OFS = "+"                     # Create $OFS and assign a "+"

       PS> [string]$array                 # Repeat the command
       1+2+3                              # Plus signs separate the elements


    To restore the default behavior, you can assign a space (" ") to 
    the value of $OFS or delete the variable. This command deletes the
    variable and then verifies that the separator is a space.
        
       PS> Remove-Variable OFS            # Delete $OFS
       PS>

       PS> [string]$array                 # Repeat the command
       1 2 3                              # Spaces separate the elements
       

$OutputEncoding
---------------
       Determines the character encoding method that Windows PowerShell 
       uses when it sends text to other applications. 

       For example, if an application returns Unicode strings to Windows
       PowerShell, you might need to change the value to UnicodeEncoding
       to send the characters correctly.

        Valid values: Objects derived from an Encoding class, such as
                      ASCIIEncoding, SBCSCodePageEncoding, UTF7Encoding, 
                      UTF8Encoding, UTF32Encoding, and UnicodeEncoding.

        Default: ASCIIEncoding object (System.Text.ASCIIEncoding)

    EXAMPLES

       This example shows how to make the FINDSTR command in Windows
       work in Windows PowerShell on a computer that is localized for
       a language that uses Unicode characters, such as Chinese. 

       The first command finds the value of $OutputEncoding. Because the
       value is an encoding object, display only its EncodingName property.
         
          PS> $OutputEncoding.EncodingName  # Find the current value
          US-ASCII

       In this example, a FINDSTR command is used to search for two Chinese
       characters that are present in the Test.txt file. When this FINDSTR
       command is run in the Windows Command Prompt (Cmd.exe), FINDSTR finds
       the characters in the text file. However, when you run the same
       FINDSTR command in Windows PowerShell, the characters are not found
       because the Windows PowerShell sends them to FINDSTR in ASCII text, 
       instead of in Unicode text.

          PS> findstr <Unicode-characters>  # Use findstr to search.
          PS>                               # None found.

        
       To make the command work in Windows PowerShell, set the value of 
       $OutputEncoding to the value of the OutputEncoding property of the
       console, which is based on the locale selected for Windows. Because 
       OutputEncoding is a static property of the console, use
       double-colons (::) in the command.

          PS> $OutputEncoding = [console]::outputencoding
          PS>                               # Set the value equal to the
                                              OutputEncoding property of the
                                              console.
          PS> $OutputEncoding.EncodingName               
          OEM United States
                                            # Find the resulting value.
     
       As a result of this change, the FINDSTR command finds the characters.

          PS> findstr <Unicode-characters>               
          test.txt:         <Unicode-characters>        

					# Use findstr to search. It find the
                                          characters in the text file.



$ProgressPreference
-------------------
	Determines how Windows 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 depict the status of a command.

        Valid values:
	    Stop:               Does not display the progress bar. Instead,
                                it displays an error message and stops executing.

     	    Inquire:            Does not display the progress bar. Prompts
                                for permission to continue. If you reply
                                with Y or A, it displays the progress bar.

            Continue:           Displays the progress bar and continues with
            (Default)           execution.

            SilentlyContinue:   Executes the command, but does not display
                                the progress bar.


$PSEmailServer
--------------
       Specifies the default e-mail server that is used to send e-mail 
       messages. This preference variable is used by cmdlets that send
       e-mail, such as the Send-MailMessage cmdlet.  


$PSSessionApplicationName
---------------------------
       Specifies the default application name for a remote command
       that uses WS-Management technology.

       The system default application name is WSMAN, but you can use this
       preference variable to change the default. 

       The application name is the last node in a connection URI. For
       example, the application name in the following sample URI is
       WSMAN.

           http://Server01:8080/WSMAN


       The default application name is used when the remote command
       does not specify a connection URI or an application name.   

       The WinRM service uses the application name to select a listener
       to service the connection request. The value of this parameter
       should match the value of the URLPrefix property of a listener
       on the remote computer.

       To override the system default and the value of this variable,
       and select a different application name for a particular session,
       use the ConnectionURI or ApplicationName parameters of the
       New-PSSession, Enter-PSSession or Invoke-Command cmdlets.      

       This preference variable is set on the local computer, but it 
       specifies a listener on the remote computer. If the application
       name that you specify does not exist on the remote computer,
       the command to establish the session fails.



$PSSessionConfigurationName
---------------------------
       Specifies the default session configuration that is used for
       PSSessions created in the current session.

       This preference variable is set on the local computer, but it 
       specifies a session configuration that is located on the remote
       computer. 

       The value of the $PSSessionConfigurationName variable is a fully
       qualified resource URI. 

       The default value: 

         http://schemas.microsoft.com/powershell/microsoft.powershell 

       indicates the Microsoft.PowerShell session configuration
       on the remote computer. 

       If you specify only a configuration name, the following schema URI
       is prepended:

           http://schemas.microsoft.com/powershell/

             
       You can override the default and select a different session
       configuration for a particular session by using the
       ConfigurationName parameter of the New-PSSession, Enter-PSSession
       or Invoke-Command cmdlets.      

       You can change the value of this variable at any time. When you
       do, remember that the session configuration that you select must
       exist on the remote computer. If it does not, the command to
       create a session that uses the session configuration fails.

       This preference variable does not determine which local session 
       configurations are used when remote users create a session that 
       connects to this computer. However, you can use the permissions
       for the local session configurations to determine which users
       may use them.


$PSSessionOption
----------------
        Establishes the default values for advanced user options in a
        remote session. These option preferences override the system
        default values for session options. 

        You can also set custom options for a particular remote session by
        using the SessionOption parameter in cmdlets that create a session,
        such as New-PSSession, Enter-PSSession, and Invoke-Command. The
        SessionOption parameter value takes precedence over the system defaults
        and the defaults that are set in this variable.

        The $PSSessionOption variable contains a PSSessionOption object       
        (System.Management.Automation.Remoting.PSSessionObject). Each 
        property of the object represents a session option. For example, 
        the NoCompression property turns of data compression during the
        session.

        To create the $PSSessionOption preference variable, use the 
        New-PSSessionOption cmdlet. Save the output in a variable called
        $PSSessionOption. 

        For example,

            $PSSessionOption = New-PSSessionOption -NoCompression
                  
        To use the $PSSessionOption preference variable in every 
        Windows PowerShell session, add a New-PSSessionOption command
        that creates the $PSSessionOption variable to your Windows
        PowerShell profile.

        For more information about the New-PSSessionOption cmdlet, see
        the help topic for New-PSSessionOption. For more information about
        remote commands and sessions, see about_Remote and about_PSSessions.
        For more information about using a profile, see about_Profiles.




$VerbosePreference
------------------
       	Determines how Windows PowerShell responds to verbose messages 
        generated by a script, cmdlet or provider, such as the messages
        generated by the Write-Verbose cmdlet. Typically, verbose messages
        describe the actions performed to execute a command. 
 
        By default, verbose messages are not displayed, but you can change
        this behavior by changing the value of $VerbosePreference.

        You can also use the Verbose common parameter of a cmdlet to display
        or hide the verbose messages for a specific command. For more
        information, type: "get-help about_commonparameters".


        Valid values:
	    Stop:               Displays the verbose message and an error
                                message and then stops executing.

     	    Inquire:            Displays the verbose message and then 
                                displays a prompt that asks you whether you
                                want to continue.

            Continue:           Displays the verbose message and then continues with execution.

            SilentlyContinue:   Does not display the verbose message. Continues executing.
            (Default)                       


    EXAMPLES

    These examples show the effect of the different values of $VerbosePreference and the use of the
    Verbose common parameter to override the preference value.
    
    This example shows the effect of the SilentlyContinue value, which is the default.

        PS> $VerbosePreference             # Find the current value.
        SilentlyContinue

        PS> Write-Verbose "Verbose message test."              
        PS>                                # Write a verbose message.
                                           # Message is not displayed.

        PS> Write-Verbose "Verbose message test." -verbose     
        VERBOSE: Verbose message test.
	                                   # Use the Verbose parameter.


    This example shows the effect of the Continue value.

        PS> $VerbosePreference = "Continue"                    
                                           # Change the value to Continue.
        PS> Write-Verbose "Verbose message test."              
                                           # Write a verbose message.
        VERBOSE: Verbose message test.                         
                                           # Message is displayed.

        PS> Write-Verbose "Verbose message test." -verbose:$false
                                           # Use the Verbose parameter with
                                             a value of $false.
        PS>                                  
                                           # Message is not displayed.


    This example shows the effect of the Stop value.

        PS> $VerbosePreference = "Stop"                        
                                           # Change the value to Stop.
        PS> Write-Verbose "Verbose message test."              
                                           # Write a verbose message.
        VERBOSE: Verbose message test.
        Write-Verbose : Command execution stopped because the shell variable "VerbosePreference"
        is set to Stop.
        At line:1 char:14
        + Write-Verbose  <<<< "Verbose message test."

       PS> Write-Verbose "Verbose message test." -verbose:$false
                                          # Use the Verbose parameter with
                                            a value of $false
       PS>                                  
                                          # Message is not displayed.

    This example shows the effect of the Inquire value.

       PS> $VerbosePreference = "Inquire"                      
                                         # Change the value to Inquire.
       PS> Write-Verbose "Verbose message test."               
       VERBOSE: Verbose message test.
                                         # Write a verbose message.
       Confirm
       Continue with this operation?
       [Y] Yes  [A] Yes to All  [H] Halt Command  [S] Suspend  [?] Help (default is "Y"): y
       PS>

       PS> Write-Verbose "Verbose message test." -verbose:$false
                                        # Use the Verbose parameter.
       PS>                              
                                        # Message is not displayed.


    
$WarningPreference
------------------
        Determines how Windows PowerShell responds to warning messages
        generated by a script, cmdlet or provider, such as the messages
        generated by the Write-Warning cmdlet.

        By default, warning messages are displayed and execution continues, 
        but you can change this behavior by changing the value of
        $WarningPreference.

        You can also use the WarningAction common parameter of a cmdlet to
        determine how Windows PowerShell responds to warnings from a particular
        command. For more information, type: "get-help about_commonparameters".


        Valid values:
	    Stop:               Displays the warning message and an error
                                message and then stops executing.

     	    Inquire:            Displays the warning message and then 
                                prompts for permission to continue. 

            Continue:           Displays the warning message and then
            (Default)           continues executing.

            SilentlyContinue:   Does not display the warning message. 
                                Continues executing.

    EXAMPLES

    These examples show the effect of the different values of 
    $WarningPreference and the use of the WarningAction common parameter
    to override the preference value.

    
    This example shows the effect of the Continue value, which is the 
    default.

            PS> $WarningPreference    # Find the current value.                           
            Continue                  

                                      # Write a warning message.
            PS> Write-Warning "This action can delete data."     
            WARNING: This action can delete data.
                                      	
                                      # Use the WarningAction parameter to 
                                      # suppress the warning for this command                                             
            PS> Write-Warning "This action can delete data." -warningaction silentlycontinue     



   This example shows the effect of the SilentlyContinue value.

            PS> $WarningPreference = "SilentlyContinue"           
                                      # Change the value to SilentlyContinue.
 
            PS> Write-Warning "This action can delete data."      
            PS>                        # Write a warning message.

       
            PS> Write-Warning "This action can delete data." -warningaction stop     
                                      # Use the WarningAction parameter to stop
                                      # processing when this command generates a
                                      # warning.         
            WARNING: This action can delete data.
            Write-Warning : Command execution stopped because the shell variable
            "WarningPreference" is set to Stop.
            At line:1 char:14
            + Write-Warning <<<<  "This action can delete data." -warningaction stop
                                 


    This example shows the effect of the Inquire value.

           PS> $WarningPreference = "Inquire"                    
                                      # Change the value to Inquire.
           PS> Write-Warning "This action can delete data."   
                                      # Write a warning message.     
           WARNING: This action can delete data.

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

           PS> Write-Warning "This action can delete data." -warningaction silentlycontinue
           PS>                         # Use the WarningAction parameter to change the
                                       # response to a warning for the current command.



     This example shows the effect of the Stop value.

           PS> $WarningPreference = "Stop"                       
                                     # Change the value to Stop.

           PS> Write-Warning "This action can delete data."      
                                     # Write a warning message.
           WARNING: This action can delete data.
           Write-Warning : Command execution stopped because the shell variable 
             "WarningPreference" is set to Stop.
           At line:1 char:14
           + Write-Warning  <<<< "This action can delete data."


           PS> Write-Warning "This action can delete data." -warningaction inquire
           WARNING: This action can delete data.

           Confirm
           Continue with this operation?
           [Y] Yes  [A] Yes to All  [H] Halt Command  [S] Suspend  [?] Help (default is "Y"):                        
                                       # Use the WarningAction parameter to change the
                                       # response to a warning for the current command.


$WhatIfPreference
------------------
       	Determines whether WhatIf is automatically enabled for every command
        that supports it. When WhatIf is enabled, the cmdlet reports the
        expected effect of the command, but does not execute the command. 

        Valid values:
	    0:                  WhatIf is not automatically enabled. To 
            (Default)           enable it manually, use the WhatIf parameter
                                of the command.
            

     	    1:                  WhatIf is automatically enabled on any
                                command that supports it. Users can use the
                                WhatIf command with a value of False to
                                disable it manually (WhatIf:$false).

    DETAILED EXPLANATION

        When a cmdlet supports WhatIf, the cmdlet reports the expected
        effect of the command, instead of executing the command. For
        example, instead of deleting the test.txt file in response to a
        Remove-Item command, Windows PowerShell reports what it would
        delete. A subsequent Get-Childitem command confirms that the file
        was not deleted.

              PS> remove-item test.txt
              What if: Performing operation "Remove-Item" on Target "Item: 
                C:\test.txt
              PS> get-childitem test.txt

              Directory: Microsoft.PowerShell.Core\FileSystem::C:


              Mode                LastWriteTime     Length     Name
              ----                -------------     ------     ----
              -a---         7/29/2006   7:15 PM         84     test.txt




    EXAMPLES

    These examples show the effect of the different values of
    $WhatIfPreference. They also show how to use the WhatIf cmdlet parameter
    to override the preference value for a specific command.
    
    This example shows the effect of the 0 (not enabled) value, which is the
    default.

             PS> $whatifpreference                     
             0                         # Check the current value.

             PS> get-childitem test.txt | format-list FullName
             FullName : C:\test.txt
                                       # Verify that the file exists.

             PS> remove-item test.txt                  
             PS>                       # Delete the file.

             PS> get-childitem test.txt | format-list -property FullName
                                       # Verify that the file is deleted.

             Get-ChildItem : Cannot find path 'C:\test.txt' because it does not exist.
             At line:1 char:14
             + get-childitem  <<<< test.txt | format-list fullname


     This example shows the effect of using the WhatIf parameter when the
     value of $WhatIfPreference is 0.

             PS> get-childitem test2.txt | format-list -property FullName 
             FullName : C:\test2.txt
                                      # Verify that the file exists.

             PS> remove-item test2.txt -whatif         
             What if: Performing operation "Remove File" on Target "C:\test2.txt".
                                      # Use the WhatIf parameter

             PS> get-childitem test2.txt | format-list -property FullName
             FullName : C:\test2.txt
                                      # Verify that the file was not deleted
                                                        
    This example shows the effect of the 1 (WhatIf enabled) value. When you
    use Remove-Item to delete a cmdlet, Remove-Item displays the path to the
    file that it would delete, but it does not delete the file.

             PS> $whatifpreference = 1                 
             PS> $whatifpreference
             1                        # Change the value.
                                      
             PS> remove-item test.txt                  
             What if: Performing operation "Remove File" on Target "C:\test.txt".
                                      # Try to delete a file.

             PS> get-childitem test.txt | format-list FullName
             FullName : C:\test.txt
                                      # Verify that the file exists.

     This example shows how to delete a file when the value of
     $WhatIfPreference is 1. It uses the WhatIf parameter with a value of
     $false.

             PS> remove-item test.txt -whatif:$false
                                      # Use the WhatIf parameter with $false.

     This example demonstrates that some cmdlets support WhatIf behavior and
     others do not. In this example, in which the value of $WhatIfPreference
     is 1 (enabled), a Get-Process command, which does not support WhatIf,
     is executed, but a Stop-Process command performs the WhatIf behavior.
     You can override the WhatIf behavior of the Stop-Process command by 
     using the WhatIf parameter with a value of $false.

            PS> $whatifpreference = 1                  
                                     # Change the value to 1.
                                                      
            PS> get-process winword  
                                    # A Get-Process command completes.

            Handles  NPM(K)    PM(K)      WS(K) VM(M)   CPU(s)     Id ProcessName
            -------  ------    -----      ----- -----   ------     -- -----------
                234       8     6324      15060   154     0.36   2312 WINWORD


           PS> stop-process -name winword              
           What if: Performing operation "Stop-Process" on Target "WINWORD (2312)".
                                    # A Stop-Process command uses WhatIf.

           PS> stop-process -name winword  -whatif:$false
           PS>                      # WhatIf:$false overrides the preference.
           
           PS> get-process winword                     
           Get-Process : Cannot find a process with the name 'winword'. Verify the process name
            and call the cmdlet again.
           At line:1 char:12
           + get-process  <<<< winword
                                    # Verify that the process is stopped.



SEE ALSO
    about_Automatic_Variables
    about_CommonParameters
    about_Environment_Variables
    about_Profiles
    about_Remote
    about_Scopes
    about_Variables
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