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About Prompts

JuanPablo Jofre|Last Updated: 11/17/2016
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2 Contributors

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 built-in Prompt function. You can customize the prompt by creating your own Prompt function and saving it in your Windows PowerShell profile.

ABOUT 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. As a best practice, return a string or an object that is formatted as a string. The maximum recommended length is 80 characters.

For example, the following prompt function returns a "Hello, World" string followed by a caret (>).

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

GETTING THE PROMPT FUNCTION

To get the Prompt function, use the Get-Command cmdlet or use the Get-Item cmdlet in the Function drive.

Functions are commands. So, you can use the Get-Command cmdlet to get functions, including the Prompt function.

For example:

PS C:\>Get-Command Prompt  

CommandType     Name                                               ModuleName  
-----------     ----                                               ----------  
Function        prompt

To get the script that sets the value of the prompt, use the dot method to get the ScriptBlock property of the Prompt function.

For example:

PS C:\>(Get-Command Prompt).ScriptBlock  

"PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "  
# .Link  
# http://go.microsoft.com/fwlink/?LinkID=225750  
# .ExternalHelp System.Management.Automation.dll-help.xml

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

(Get-Item function:prompt).ScriptBlock

THE DEFAULT PROMPT

The default prompt appears only when the Prompt function generates an error or does not return an object.

The default Windows PowerShell prompt is:

PS>

For example, the following command sets the Prompt function to $null, which is invalid. As a result, the default prompt appears.

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

Because Windows PowerShell comes with a built-in prompt, you usually do not see the default prompt.

BUILT-IN PROMPT

Windows PowerShell includes a built-in prompt function.

In Windows PowerShell 3.0, the built-in prompt function is:

function prompt  
{  
    "PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "  
}

This simplified prompt starts with "PS" followed by the current location, and one ">" for each nested prompt level.

In Windows PowerShell 2.0, 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>>>

CHANGES TO THE PROMPT

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.

HOW TO CUSTOMIZE 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 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:

03/15/2012 17:49:47>

You can also change the default Prompt function:

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 FUNCTION

Like any function, the Prompt function exists 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

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