How to make a new command in Windows PowerShell

Lets say you have a idea for a new function that you would like to implement in Window's PowerShell. In this case I made a Unix like whoami command:

function whoami
{
     [System.Security.Principal.WindowsIdentity]::GetCurrent().Name       
}

when in PowerShell it returned for me: mss/wandrus. Simple enough. Now to get the command to be usable every time an new PowerShell is opened.

 

Type within PowerShell:  Get-Variable profile | Format-List

This should give you the information on what file and directory path are needed to place your custom scripts. In this case I was given:

C:\Document and Settings\wandrus\My Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1

 

Which meant that I had to create a new folder (WindowsPowerShell) and a new script file in notepad (Microsoft.PowerShell_profile.ps1) where I've place my function.