PowerShell To Change Set Default Page

PowerShell Script To Set a New Default Page:

$site = Get-SPSite http://server/sites/sitename
$web = $site.RootWeb
$folder = $web.RootFolder
$folder.WelcomePage = "Shared%20DocumentLibrary/CustomPage.aspx")
$folder.update()
$web.Dispose()
$site.Dispose()

Thanks