Describes the Prompt function and demonstrates how to create a custom (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

C:\Windows>powershell get-help about_properties -full

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