Powershell script: bulk add users to SharePoint group

Note - You may need to check the Claims prefix

Here's the PowerShell:

<# Instructions:

Create a Users.txt in this format (all in one column):

    i:0#.w|domain\aparnis

    i:0#.w|domain\candlandan

    i:0#.w|domain\stivj001

    i:0#.w|domain\attaj001

    i:0#.w|domain\marchorovitz

    etc

Populate the variables

#>

## Adding snap-in

Add-PSSnapin "Microsoft.SharePoint.PowerShell"

# Variables

$group = "External Readers"

$siteCollUrl = "https://extranet.domain/groups/Board-of-Supervisors/"

$loc = "C:\scripts"        

$Users = Get-Content "$loc\Users.txt"        

$web = Get-SPWeb -identity $siteCollUrl

# code

foreach ($User in $Users) {

    $web.EnsureUser($User)        

    Set-SPUser -Identity $User -Web $siteCollUrl -Group $group         

}

# Dispose the web object

$Web.Dispose()