Copy account's (users and groups), to an other site. Edit login's prefix part in the same time.

config.ini

[GENERAL]
url_communities=http://rbla-sp2010-002/sites/communaute
url_one=http://rbla-sp2010-002/sites/test_one_romain
namingconvention_prefix=SG-ONE-
namingconvention_suffix=-R
newgroupowners=rbla\administrator
logfilepath=C:\Users\blanchardro\Desktop\GroupMigrationLogs\
logfilename=group_migration
numberoflogfilestokeep=30

CopyUsersAndGroups.ps1

# ----------------------------------------------
# Author: Romain Blanchard
# Date: 29.03.2013
# Description: Copy account's (users and groups), to an other site. Edit login's prefix part in the same time. 
# ----------------------------------------------

## Import Powershell module if the script is launched from normal powershell commandline
Add-PSSnapin Microsoft.SharePoint.PowerShell -erroraction SilentlyContinue

## Function that reads the INI configuration file
function Convert-IniFile ($file)
{
    $REGEX_INI_COMMENT_STRING = ";"
    $REGEX_INI_SECTION_HEADER = "^\s*(?!$($REGEX_INI_COMMENT_STRING))\s*\[\s*(.*[^\s*])\s*]\s*$"
    $REGEX_INI_KEY_VALUE_LINE = "^\s*(?!$($REGEX_INI_COMMENT_STRING))\s*([^=]*)\s*=\s*(.*)\s*$"

    $ini = @{}
    switch -regex -file $file {
        "$($REGEX_INI_SECTION_HEADER)" {
            $section = $matches[1]
            $ini[$section] = @{}
        }
        "$($REGEX_INI_KEY_VALUE_LINE)" {
            $name,$value = $matches[1..2]
            if ($name -ne $null -and $section -ne $null)
            {
                $ini[$section][$name] = $value
            }
        }
    }
    $ini
}

## Function to create a new SharePoint group
function New-SPGroup {
	 [CmdletBinding()]
    Param(
    [string]$Web,
    [string]$GroupName,
    [string]$OwnerName,
    [string]$MemberName,
    [string]$Description
    )
    $SPWeb = Get-SPWeb $Web
    if ($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
}
cls

## Read the INI config file (be carefull beacause we read in the current console location)
$iniFile = Convert-IniFile("config.ini")

## Prepare LOGS
$date = Get-Date -format yyyyMMdd
$logfilename = $iniFile["GENERAL"]["logfilename"]
$logfilename_new = $logfilename + "_" + $date + ".csv"
$logfilepath = $iniFile["GENERAL"]["logfilepath"]
$numberoflogfilestokeep = $iniFile["GENERAL"]["numberoflogfilestokeep"]
$logfile = $logfilepath + $logfilename_new
$logfile_exist = Test-path $logfile
if ($logfile_exist -eq "True"){ remove-item -path $logfile -Confirm:$false }
write-output "Web;Group;Message" | out-file -filepath $logfile -append

## Delete old logs files
$files = Get-ChildItem $logfilepath -Recurse | where-object {$_.Name -ilike "$logfilename*"} | Sort-Object Name
$c = $files.Count
if ($c -gt $numberoflogfilestokeep)
{
	do
	{
		$filepath = $logfilepath + $files[0]
		remove-item -path $filepath -Confirm:$false
		$files = Get-ChildItem $logfilepath -Recurse | where-object {$_.Name -ilike "$logfilename*"} | Sort-Object Name
		$c--
	}
	until ($c -le $numberoflogfilestokeep)
}

## Get/Set script variables
$url_communities = $iniFile["GENERAL"]["url_communities"]
$url_one = $iniFile["GENERAL"]["url_one"]
$namingconvention_prefix = $iniFile["GENERAL"]["namingconvention_prefix"]
$namingconvention_suffix = $iniFile["GENERAL"]["namingconvention_suffix"]
$newgroupowners = $iniFile["GENERAL"]["newgroupowners"]
$CommunitiesSite = Get-SPSite $url_communities
$CommunitiesWeb = $CommunitiesSite.OpenWeb()
$ONESite = Get-SPSite $url_one
$ONEWeb = $ONESite.OpenWeb()

## Foreach site in communities site collection
foreach($web in $CommunitiesWeb.Webs)
{
	try
	{
		## Clean web's title name for group naming convention
		$webname = $web.Title.Replace("'","").Replace("\","").Replace("/","").Replace("[","").Replace("]","").Replace(":","").Replace("|","").Replace("<","").Replace(">","")
		$webname = $webname.Replace("+","").Replace("=","").Replace(";","").Replace(",","").Replace("?","").Replace("*","").Replace("@","").Replace(" ","")
		$groupname = $namingconvention_prefix + $webname + $namingconvention_suffix
		$groupdescription = "Users of $web website."
		
		## Select group in target website if already exist
		if ($ONEWeb.SiteGroups[$groupname] -ne $null)
		{
			$currentgroup = $ONEWeb.SiteGroups[$groupname]
		}
		
		## Create and select group in target website if doesn't exist
		else
		{
			$currentgroup = New-SPGroup -Web $url_one -GroupName $groupname -OwnerName $newgroupowners -MemberName $newgroupowners -Description $groupdescription
			write-output "$ONEWeb;$groupname;$groupname group has been created." | out-file -filepath $logfile -append
		}
		
		## Foreach groups in the current website
		foreach ($group in $web.Groups)
		{
			## Does not select sharepoint useless groups
			if (($group.Name -notcontains "Style Resource Readers") -or ($group.Name -eq "Viewers"))
			{				
				foreach ($user in $group.Users)
				{
					## if real user
					if($user.UserLogin.Contains("red\"))
					{
						$user = $user.UserLogin.Replace("i:0#.w|","")
						
						try
						{
							$currentgroup.AddUser($user, $user.Email, $user.Name,"")
							write-output "$web;$currentgroup;$user has been added to the group $currentgroup." | out-file -filepath $logfile -append
						}
						catch
						{
							write-output "$web;$currentgroup;Cannot add user $user to the group $currentgroup. More: $_" | out-file -filepath $logfile -append
						}
						
					}
					elseif ($user.UserLogin.Contains("c:0"))
					{
						$sid = $user.UserLogin.Replace("c:0+.w|","")
						$securitygroupname = [adsi]"LDAP://<SID=$sid>"
						$user = $securitygroupname.Properties.Item("CN")
						
						$ensured_user = $web.EnsureUser($user)					
						$currentgroup.AddUser($ensured_user)
						write-output "$web;$currentgroup;$user security group has been added to the group $currentgroup." | out-file -filepath $logfile -append
					}
				}
			}
		}
	}
	catch
	{
		write-output "$web;N/A;$_" | out-file -filepath $logfile -append
	}
}