PowerShell For Fun

What Can Tweaking Your Prompt Do For You?

Windows PowerShell have a default prompt in one color (usually gray) that tells you your current working directory. This is OK, but you can do much more with the prompt.
1. All sorts of information can be displayed (machine name, host name, user name, time & date ...)
2. The prompt can use colors
3. You can also manipulate the windows title to dispaly more information.
4. Other RawUI operation is allowed (move cursor)

Why Bother?

Beyond looking cool, it's often useful to keep track of system information.
1. Get your current working directory (how many files in current directory)
2. Current system time, how many process is running
2. If you use my su.msh, you would like to know you current windows identity
3. If you use my powershell remoting, different color helps distingish between local host and remote host.
4. Colorizing your prompt is the ability to quickly spot the prompt when you use scroll console.

First step: Profile and prompt function

Windows PowerShell use Profile to customize user environment. For more detail, about profile
The Story Behind the Naming and Location of PowerShell Profiles:
http://www.leeholmes.com/blog/TheStoryBehindTheNamingAndLocationOfPowerShellProfiles.aspx

1. You can have different prompt for different shell (Maybe you use makeshell.exe generated you own shell)
2. If you have different prompt function defined in multiple profile, the last one excuted take effect
Remember the excution order is

1. "All users" profile is loaded from "<Installation Directory>\profile.ps1"
   
2. "All users," host-specific profile is loaded from "<Installation Directory>\Microsoft.PowerShell_profile.ps1"
   
3. Current user profile is loaded from "<My Documents>\WindowsPowerShell\profile.ps1"
   
4. Current User, host-specific profile is loaded from "<My Documents>\WindowsPowerShell\Microsoft.PowerShell_profile.ps1"

Edit 09-29-2006

Windows PowerShell RC2 changed profile location to

<My documents>\WindowsPowerShell
Now you can customize you prompt in you profile (say <my document>\psconfigurtion\profile.ps1)
this is typical prompt function looks like:

function prompt
{
    "PS " + $(get-location) + "> "
}

You can do whatever you want in prompt function. But remember
1) Always return a [string], otherwise Windows PowerShell will use default "PS> " prompt.
2) Try to limit your prompt in one (short) line
3) Host will evaluate prompt frequently, so don't do crazy stuff to slow down your work.

Colorized prompt

function prompt
{
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor Magenta
    return " "
}

Random color

function prompt
{
    $random = new-object random
    $color=[System.ConsoleColor]$random.next(1,16)
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor $color
    return " "
}

Cursor Movement
Display current  time at the end of prompt line (this will mess up you console buffer)

function prompt
{
    $oldposition = $host.ui.rawui.CursorPosition
    $Endline = $oldposition
    $Endline.X+=60
    $host.ui.rawui.CursorPosition = $Endline
    Write-Host $(get-date).Tostring("yyyy-MM-dd HH:mm:ss")
    $host.ui.rawui.CursorPosition = $oldposition
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor Magenta
    return " "
}

Use Window Title
Show current user, host, current line number

$global:CurrentUser = [System.Security.Principal.WindowsIdentity]::GetCurrent()
function prompt
{
    $host.ui.rawui.WindowTitle = $CurrentUser.Name + " " + $Host.Name + " " + $Host.Version + " Line: " + $host.UI.RawUI.CursorPosition.Y
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor Magenta
    return " "
}

Make some noise
if your command  take very long time to run, beep when it is done.

function prompt
{
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor Magenta
    return "`a "
}

More information
Count number of files(or items) in current path and number of process running

function prompt
{
    $host.ui.rawui.WindowTitle = "Files: " + (get-childitem).count + " Process: " + (get-process).count
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor Magenta
    return " "
}

Something for readers:
1. laptop battery is low ! (Edit 2006-07-21: Already done by Musings of a PC)
2. You got new mail !
3. LAN cable disconnected !

Have Fun

Reference:
http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/

Tags: msh    monad   powershell