about_Prompts

TOPIC
	about_Prompts

SHORT DESCRIPTION
	Describes the Prompt function and demonstrates how to create a custom 
	Prompt function.

  
LONG DESCRIPTION
	The Windows PowerShell command prompt indicates that Windows PowerShell 
	is ready to run a command: 

		PS C:\>


	The Windows PowerShell prompt is determined by the Prompt function. You 
	can customize the prompt by creating your own Prompt function. Then, you
	can save this function in your Windows PowerShell profile.

   
  The Prompt Function

	The Prompt function determines the appearance of the Windows PowerShell 
	prompt. Windows PowerShell comes with a built-in Prompt function, but
	you can override it by defining your own Prompt function.


	The Prompt function has the following syntax:

		function prompt { <function-body> }


	The Prompt function must return an object, typically a string. We 
	recommend that it return a string or an object that is formatted as a 
	string. The string should fit on an 80-character line.


	For example:

		PS C:\> function prompt {"Hello, World > "}
		Hello, World > 

  
	Like all functions, the Prompt function is stored in the Function: drive. 
	To display the code in the current Prompt function, type:

		(get-item function:prompt).definition


	This command uses the Get-Item cmdlet to display the Prompt item in the 
	Function: drive. Then, it uses dot notation to display the value of the
	Definition property of the Prompt function. 


  The Default Prompt 

	The default Windows PowerShell prompt is:

		PS>


	This prompt appears only when the prompt function generates an error or 
	when the prompt function does not return a string or object.

		PS C:\> function prompt {$null}
		PS>


	Because Windows PowerShell comes with a built-in prompt, you usually do 
	not see the default prompt until you write your own prompt function.


  The Built-in Prompt

 
	Windows PowerShell includes a built-in prompt function that creates the 
	familiar prompts. The built-in prompt function is:

		function prompt
		{
			$(if (test-path variable:/PSDebugContext) { '[DBG]: ' } 

			else { '' }) + 'PS ' + $(Get-Location) `

			+ $(if ($nestedpromptlevel -ge 1) { '>>' }) + '> '
	} 


	The function uses the Test-Path cmdlet to determine whether the 
	$PSDebugContext automatic variable is populated. If $PSDebugContext is 
	populated, you are in debugging mode, and "[DBG]" is added to the prompt,
	as follows:

		[DBG] PS C:\ps-test>
	
	 
	If $PSDebugContext is not populated, the function adds "PS" to the 
	prompt. And, the function uses the Get-Location cmdlet to get the current
	file system directory location. Then, it adds a right angle bracket (>). 
	For example:	
		 
		PS C:\ps-test>  


	If you are in a nested prompt, the function adds two angle brackets (>>) 
	to the prompt. (You are in a nested prompt if the value of the 
	$NestedPromptLevel automatic variable is greater than 1.)


	For example, when you are debugging in a nested prompt, the prompt 
	resembles the following prompt:

		[DBG] PS C:\ps-test>>>


	The Enter-PSSession cmdlet prepends the name of the remote computer to
	the current Prompt function.  When you use the Enter-PSSession cmdlet to
	start a session with a remote computer, the command prompt changes to
	include the name of the remote computer. For example:

		PS Hello, World> Enter-PSSession Server01

		[Server01]: PS Hello, World>


	Other Windows PowerShell host applications and alternate shells might 
	have their own custom command prompts.


	For more information about the $PSDebugContext and $NestedPromptLevel 
	automatic variables, see about_Automatic_Variables.
	

  Customizing the Prompt

	To customize the prompt, write a new Prompt function. The function is not 
	protected, so you can overwrite it. 
 

	To write a prompt function, type the following:

		function prompt { }


	Then, between the curly braces, enter the commands or the string that 
	creates your prompt.


	For example, the following prompt includes your computer name:

		function prompt {"PS [$env:COMPUTERNAME]> "}


	On the Server01 computer, the prompt resembles the following prompt:

		PS [Server01] >


	The following prompt function includes the current date and time:

		function prompt {"$(get-date)> "}


	The prompt resembles the following prompt:

		01/01/2008 17:49:47>


	You can also modify the default Prompt function:


		function prompt
		{
			$(if (test-path variable:/PSDebugContext) { '[DBG]: ' } 

			else { '' }) + "$(get-date)" `

			+ $(if ($nestedpromptlevel -ge 1) { '>>' }) + '> '
	} 

  
	For example, the following modified Prompt function adds "[ADMIN]:" to
	the built-in Windows PowerShell prompt when Windows PowerShell is opened
	by using the "Run as administrator" option:

		function prompt 
		{
			$identity = [Security.Principal.WindowsIdentity]::GetCurrent()
			$principal = [Security.Principal.WindowsPrincipal] $identity

			$(if (test-path variable:/PSDebugContext) { '[DBG]: ' } 

			elseif($principal.IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator"))
				{ "[ADMIN]: " }

			else { '' }) + 'PS ' + $(Get-Location) + $(if ($nestedpromptlevel -ge 1) { '>>' }) + '> '
	}



	When you start Windows PowerShell by using the "Run as administrator"
	option, a prompt that resembles the following prompt appears:
			
		[ADMIN]: PS C:\ps-test>


	The following Prompt function displays the history ID of the next
	command. To view the command history, use the Get-History
	cmdlet.   

		function prompt
		{
			 # The at sign creates an array in case only one history item exists.
			 $history = @(get-history)
			 if($history.Count -gt 0)
			 {
				$lastItem = $history[$history.Count - 1]
				$lastId = $lastItem.Id
			 }

			 $nextCommand = $lastId + 1
			 $currentDirectory = get-location
			 "PS: $nextCommand $currentDirectory >"
	}



	The following prompt uses the Write-Host and Get-Random cmdlets to create
	a prompt that changes color randomly. Because Write-Host writes to the 
	current host application but does not return an object, this function 
	includes a Return statement. Without it, Windows PowerShell uses the 
	default prompt, "PS>".

		function prompt
		{
			$color = get-random -min 1 -max 16
			write-host ("PS " + $(get-location) +">") -nonewline -foregroundcolor $color
			return " "
	}


  Saving the Prompt
	
	Like any function, the Prompt function applies only in the current 
	session. To save the Prompt function for future sessions, add it to your
	Windows PowerShell profiles. For more information about profiles, 
	see about_Profiles.


SEE ALSO
	Get-Location
	Enter-PSSession
	Get-History
	Get-Random
	Write-Host
	about_Profiles
	about_Functions
	about_Scopes
	about_Debuggers
	about_Automatic_Variables