Guest Use Login Picture

This is the script I use to set a picture for the user. You can set any path to any user as far as I'm aware, this has worked for me all the way up to Mojave so far! Hope it helps!

Note: I have not tried this with a Guest Account

#!/bin/bash

# Reset User Default Photo JUST incase
#########################################################################################

# Delete the hex entry for jpegphoto
dscl . delete /Users/USERNAMEHERE jpegphoto
dscl . delete /Users/USERNAMEHERE Picture

# Set New Photo
dscl . create /Users/USERNAMEHERE Picture "/PATH/TO/PICTURE/userdefault.jpg"

# Force system to rebuild the caches including local directory
kextcache -system-caches


exit

Thanks for the comment. Unfortunately, 'Other', and System Administrator never have a directory in the Users folder, and guest only does if they are logged in. Scripts that rely on subdirs within Users will not work for this problem.