Change master page for all sites

Question

I have a new master which has to be applied on all of my sites. But I don't know to change the content of my odler master page in database (for all sites) via Powershell. I know how iterate my sites and modify the url of the master page, but me I just want to change the CONTENT of my master page.

Thanks for your help

Answer 1

This should work. This adds to all Farm your master page.

foreach($webApp in (Get-SPWebApplication))
  foreach($site in $webApp.Sites)

  # check compatibility level -> 14 if SP2010, 15 if SP2013
  if ($site.CompatibilityLevel –eq 15) 
    foreach ($web in $site.AllWebs)
      if ($web.Exists)
        $web.SiteLogoUrl = "/SiteAssets/logo.png"
        $web.SiteLogoDescription = "My PowerShell Site"
        $web.MasterUrl = "/_catalogs/masterpages/seattle.master"
        $web.CustomMasterUrl = "/_catalogs/masterpages/seattle.master"

$web.Update()

$web.Dispose()
$site.Dispose()