Add-AclAccessRule.ps1

function Add-AclAccessRule {
<#
.SYNOPSIS
    Adds an access rule to an existing ACL on a folder or file.
.DESCRIPTION
    Use .net methods to get the current ACL of the file or folder then generates a new rule
    to which is added to the ACL of the file system object
.EXAMPLE
    $splat = @{
        Path = 'C:\Logs'
        IdentityReference = 'Everyone'
        AccessControlType = 'Allow'
        FileSystemRights = 'Modify'
        InheritanceFlags = 'ObjectInherit,ContainerInherit'
        PropagationFlags = 'None'
    }

    Add-AclAccessRule @splat
#>
    [CmdletBinding()]
    param(
    [Parameter(Mandatory=$true)]
    [ValidateNotNullOrEmpty()]
    [string]$Path,

    [Parameter(Mandatory=$true)]
    [ValidateNotNullOrEmpty()]
    [Alias('Username', 'User')]
    [string]$IdentityReference,

    [Parameter(Mandatory=$true)]
    [ValidateSet('Allow','Deny')]
    [string]$AccessControlType,

    [Parameter(Mandatory=$true)]
    [ValidateSet('Modify','FullControl','Read','Write','ReadAndExecute','TakeOwnership')]
    [string]$FileSystemRights,

    [Parameter(Mandatory=$false)]
    [ValidateSet('ObjectInherit','ContainerInherit','None','ObjectInherit,ContainerInherit')]
    [string]$InheritanceFlags,

    [Parameter(Mandatory=$false)]
    [ValidateSet('InheritOnly','None','NoPropagateInherit')]
    [string]$PropagationFlags

    )
    
    begin {

        $ACL = (Get-Item $Path).GetAccessControl('Access')

        $arFileSystemRights = [System.Security.AccessControl.FileSystemRights]"$FileSystemRights"
        $arType =[System.Security.AccessControl.AccessControlType]::$AccessControlType
        $arUser = New-Object System.Security.Principal.NTAccount("$IdentityReference") 

        if ($InheritanceFlags) {
            $arInheritanceFlag = [System.Security.AccessControl.InheritanceFlags]"$InheritanceFlags"
        }

        if ($PropagationFlags) {
            $arPropagationFlag = [System.Security.AccessControl.PropagationFlags]::$PropagationFlags
        }

        $accessRule= New-Object System.Security.AccessControl.FileSystemAccessRule ($arUser, $arFileSystemRights, $arInheritanceFlag, $arPropagationFlag, $arType)

        Write-Verbose -Message "Access Rule [$accessRule]"
    }
    
    process {
        $ACL.AddAccessRule($accessRule)

        Write-Verbose -Message "Modify ACL [$ACL]"

        try {
            Set-ACL -Path $Path -AclObject $ACL
        }
        catch  {
            Write-Error "ACL failed to apply new Rule"
        }
        
    }
    
    end {
    }
}