Create Site Permission Groups and Add Users for SharePoint - Powershell

The following post is a PowerShell script to create or remove site level permission groups and add users to those group for SharePoint.
Function to create a permission group...

function Create-SPGroupInWeb  
{  
    param ($url, $groupName, $permissionLevel, $description)  
    try{
        $web = Get-SPWeb -Identity $url 
        if($web -ne $null){
            if ($web.SiteGroups[$groupName] -ne $null)  
            {  
                write-Host -f red "Group $groupName already exists!"
            }  
            else  
            {  
                $web.SiteGroups.Add($groupName, $web.Site.Owner, $web.Site.Owner, $description)  
                $group = $web.SiteGroups[$groupName]  
                $roleAssignment = new-object Microsoft.SharePoint.SPRoleAssignment($group)  
                $roleDefinition = $web.Site.RootWeb.RoleDefinitions[$permissionLevel]  
                $roleAssignment.RoleDefinitionBindings.Add($roleDefinition)  
                $web.RoleAssignments.Add($roleAssignment)  
                $web.Update()  
                write-Host "Group $groupName created successfully" 
            }  

            $web.Dispose() 
        }
    }
    catch [System.Exception]
    {
        write-host -f red $_.Exception.ToString()
    }
}

Function to remove permission groups by name...

function Remove-SPGroupInWeb  
{  
    param ([string]$url, [string]$groupName)  
    try{
        $web = Get-SPWeb -Identity $url 
        if($web -ne $null){
            if($web.SiteGroups[$groupName] -ne $null){
                write-Host -f yellow "Removing site group $groupName"
                $web.SiteGroups.Remove($groupName)
            }
            $web.Update()
            $web.Dispose() 
        }
    }
    catch [System.Exception]
    {
        write-host -f red $_.Exception.ToString()
    }
}

Function to add users to the group...

function Add-User
{
    param ($url, $groupName, $userName) 
    try{
        $web = Get-SPWeb $url
        if($web -ne $null){
            $MyGrp = $web.SiteGroups[$groupName]
            $user = $web.Site.RootWeb.EnsureUser($userName)
            $MyGrp.AddUser($user)
            write-Host "$userName added to $groupName" 
            $web.Update()
            $web.Dispose()
        }
    }
    catch [System.Exception]
    {
        write-host -f red $_.Exception.ToString()
    }
}

How to call the functions...

Remove-SPGroupInWeb -url "http://my-webApp:port/" -groupName "New Group"

Create-SPGroupInWeb -url "http://my-webApp:port/" -groupName "New Group" -permissionLevel "Read" -description "My New Group Description"

Add-User -url "http://my-webApp:port/" -groupName "New Group"-userName "domain\myUserName" 

As for the permission level of the group your going to create, For full control, send "Full Control" as the permissionLevel parameter. Running this code directly in SharePoint Management Shell wont be a problem.
Incase you are running it on Windows PowerShell, run this command as well... "Add-PSSnapin "Microsoft.SharePoint.PowerShell"


If you have any questions. I'll be glad to reply with what ever I know :) .