Disclaimer: This post and function is 100% taken from the book by Gary Lapointe and Shannon Bray entitled “Automating Microsoft SharePoint 2010 Administration with Windows PowerShell 2.0.”

This post goes hand in hand with my recent post called “Retrieve SharePoint Groups using PowerShell.”  In that post, we used a simple PowerShell Function to retrieve an SP Group and return the object in our command window.  In this function, we’re going to take the work a step further – we will use our function to create a new SharePoint Group.

Again, I have taken the code from Gary and Shannon’s book – the only addition I have made is comment-based help.  Since I intend to use these functions, I like to have help so I can go back and see examples and things like that.

The function provided in the book is very nice, it consists of 5 parameters and will has some built-in error handling – example: if the group already exists it will tell you so…

I have tested this a few times, and the function works great!

Without further ado, here’s the function:

function New-SPGroup {
<#
.Synopsis
	Use New-SPGroup to create a SharePoint Group.
.Description
	This function uses the Add() method of a SharePoint RoleAssignments property in an SPWeb to create a SharePoint Group.
.Example
	C:\PS>New-SPGroup -Web http://intranet -GroupName "Test Group" -OwnerName DOMAIN\User -MemberName DOMAIN\User2 -Description "My Group"
	This example creates a group called "Test Group" in the http://intranet site, with a description of "My Group".  The owner is DOMAIN\User and the first member of the group is DOMAIN\User2.
.Notes
	Name: New-SPGroup
	Author: Ryan Dennis
	Last Edit: July 18th 2011
	Keywords: New-SPGroup
.Link
	http://www.sharepointryan.com
 	http://twitter.com/SharePointRyan
.Inputs
	None
.Outputs
	None
#Requires -Version 2.0
#>
	[CmdletBinding()]
	Param(
	[Microsoft.SharePoint.PowerShell.SPWebPipeBind]$Web,
	[string]$GroupName,
	[string]$OwnerName,
	[string]$MemberName,
	[string]$Description
	)
	$SPWeb = $Web.Read()
	if ($SPWeb.SiteGroups[$GroupName] -ne $null){
		throw "Group $GroupName already exists!"	
	}
	if ($SPWeb.Site.WebApplication.UseClaimsAuthentication){
		$op = New-SPClaimsPrincipal $OwnerName -IdentityType WindowsSamAccountName
		$mp = New-SPClaimsPrincipal $MemberName -IdentityType WindowsSamAccountName
		$owner = $SPWeb | Get-SPUser $op
		$member = $SPWeb | Get-SPUser $mp
	}
	else {
	$owner = $SPWeb | Get-SPUser $OwnerName
	$member = $SPWeb | Get-SPUser $MemberName
	}
$SPWeb.SiteGroups.Add($GroupName, $owner, $member, $Description)
$SPGroup = $SPWeb.SiteGroups[$GroupName]
$SPWeb.RoleAssignments.Add($SPGroup)
$SPWeb.Dispose()
return $SPGroup
}