I don't know python, but others do. Can you post the script or the relevant parts of it at least? I'm wondering if you're just running up against the aggressive preference caching.

Sure, it's a script that's been mentioned here and available at (https://github.com/grahamgilbert/macscripts/tree/master/set_desktops)

#!/bin/sh



#!/usr/bin/python



'''Uses Cocoa classes via PyObjC to set a desktop picture on all screens.

Tested on Mountain Lion and Mavericks. Inspired by Greg Neagle's work: https://gist.github.com/gregneagle/6957826



See:

https://developer.apple.com/library/mac/documentation/cocoa/reference/applicationkit/classes/NSWorkspace_Class/Reference/Reference.html



https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/Reference/Reference.html



https://developer.apple.com/library/mac/documentation/cocoa/reference/applicationkit/classes/NSScreen_Class/Reference/Reference.html

'''



from AppKit import NSWorkspace, NSScreen

from Foundation import NSURL

import argparse

import sys



parser = argparse.ArgumentParser(description='Sets the desktop picture on all screens')

parser.add_argument('--path', help='The path of the image')

args = vars(parser.parse_args())



if args['path']:

    picture_path = args['path']

else:

    print >> sys.stderr, 'You must supply a path for the desktop picture'

    exit(-1)



# generate a fileURL for the desktop picture

file_url = NSURL.fileURLWithPath_(picture_path)



# make image options dictionary

# we just make an empty one because the defaults are fine

options = {}



# get shared workspace

ws = NSWorkspace.sharedWorkspace()



# iterate over all screens

for screen in NSScreen.screens():

    # tell the workspace to set the desktop picture

    (result, error) = ws.setDesktopImageURL_forScreen_options_error_(

                file_url, screen, options, None)

    if error:

        print error

        exit(-1)

@tommrkr we use a version of Graham's script. But tigger it via a LaunchAgent at login.

I think the issue is whom is logged into the Macs at the time of execution.

Maybe it needs a user logged in for something it's referencing to exist?
What does it do on a machine with a user logged in but still running from the JSS normally on the recurring trigger?
Sorry I also don't do Python, just guessing as to the machine differences when it's being run.

Yea, I'm a bit out of my depth with python. Just remember that a machine will 'check-in' if it's logged out. Since the policy will only run once, this could point directly to what folks are already point to. There should be policy logs you can check. Regardless, you also should be able to change the event trigger from "recurring check-in" to "login" and see if that helps with the policy as you have it. You will have to clear your policy logs thouhg as the JSS will remember that it's already run the policy on a given unit.

P.S> I'm getting the sense that I really should learn python.

Thanks everyone for your input. I did make sure that the account in question was logged in to all of the machines and ran the script on check-in to no avail. I also tried killing cfprefsd and dock to rule out caching issues. Still no luck.

I've also tried calling the sqlite db, trying to change via osascript, but never had any luck via policy. Was hoping the python script would be the way to go, but I think I'm missing a piece to the puzzle.

I will try it as a login hook and see if that makes a difference.

Update:

Moving it to the login hook, I got an error:

_RegisterApplication(), FAILED TO establish the default connection to the WindowServer, _CGSDefaultConnection() is NULL. mac

Added sudo -u username to the command calling the script and all was right with the world. I guess the script couldn't touch the environment as root. Right now, I'm really only concerned with one account getting the push, but I decided to pull the user from the system and passing as a variable instead of just using the username

#!/bin/sh



loggedinuser=$(ls -ltr /dev/console | awk '{print $3}')

sudo -u "$loggedinuser" python /Users/Shared/set_desktops.py --path /Users/Shared/DefaultDesktop03.jpg

Thanks to everyone for helping me get the wheels spinning again!