I am trying desperately to change the login screen image (defaults to a blurred image) to any other image that I want. I have already tried:

And I can garantee you, none of them work any more in macOS Sierra, they used to in previous versions of the OS, but not anymore.

I would really appreciate some help!


You can do this by editing system .plist's through defaults (tedious), or you can use Onyx for this (simple). Onyx is quite a capable utility and it's free - if you like it, donate a bit for the Author though he does a great job with this app.

You can do this by launching Onyx, entering your admin password and choosing the login tab: Onyx login tab

There are also tons of other options you can check out. Tinkering with Onyx is quite secure since you can roll back to defaults with one button press, so don't worry about bricking something - but still be aware what you click ;)

If you want to do this without any extra software, you would need to edit your defaults by importing/exporting them. I wrote a script for the exporting part, it writes each domain into a separate file for easier overview and keeps system namespace/user namespace separate + sorts out system/apple defaults from those that were changed/set by any software the user installed.

I use it mostly for filtering crap leftovers from tests to keep the defaults tidy- since the background/login is also set there- that's what you need to edit.

In some cases, you might need to parse binary .plist files, and this needs an editor that can parse those- easily done with TextMate (or Xcode if in need of "vanilla"). Hope that solves your problem.

Script is here: export-defaults.zsh

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    Thanks but I would rather use a "vanilla" version, I don't want to install any additional software to perform this task, sorry. – Kutyel Apr 25 '17 at 8:21
  • You don't have to install anything- like I mentioned above- to do this by hand you need to change system defaults accordingly, Onyx does the same for you- hence it's simpler. If you don't know how to work with defaults I strongly recommend you use Onyx. – PJJ Apr 25 '17 at 8:37
  • Depends on your idea of installation - its a binary you can run without installation and delete it after without any leftovers, so there is no installation, it's not a .pkg file. What's your point here? – PJJ Apr 25 '17 at 9:11
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    Ok, I downloaded Onyx and used it without installing it, I understand now what you meant and it worked, my apologies and thanks again! I am curious though, is really that difficult to override that specific default? Maybe is just a couple commands I'd like to know ;) – Kutyel Apr 26 '17 at 9:16
  • No apology needed, just keep openminded to any answer, you will never know. You can set most of the system stuff through defaults, there is plenty of 3rd party apps (Onyx being one) which are a fancy interface/editor to defaults, checkout dotfiles on github and check the script, you can fiddle inside those files with TextMate. You can basically do almost everything system-wise from the command-line. We could (unjustly) simplify that macOS is a fancy UI that sits on top of Darwin, which is a BSD offshot with Apple "innovations" added. – PJJ Apr 26 '17 at 11:26

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