A simple python script to allow updating all of your desktop backgrounds, for all your screens/desktops/spaces at once.

meinosxsetbackground.py

#!/usr/bin/env python

# A simple python script to allow updating all of your desktop backgrounds,
# for all your desktops/spaces at once.

# Check out http://1klb.com/blog/desktop-background-on-os-x-109-mavericks.html
# for more information. His implementation was in Ruby. I wanted to do it
# in Python.
import sys
import os
import sqlite3

line = ""

# sys.argv[0] is the program name. sys.argv[1] is the first argument
if len(sys.argv) > 1:
    line = sys.argv[1]

# if we don't already have a file to use, ask for one
if not line:
    try:
        line = raw_input(
            "Drag and drop an image file here then press 'return' or press 'control-c' to cancel: ")
    except KeyboardInterrupt:
        sys.exit()

if not line:
    print "Okay, well, we can't do this if you don't cooperate!"
    sys.exit()

print "You entered '%s'" % line

background = os.path.abspath(line.strip())

if not os.path.isfile(background):
    print "Sorry, this is not a valid file: '%s'" % background
    sys.exit()

print "Changing all desktop backgrounds to: '%s'" % background

home = os.path.expanduser("~")
desktopdb = "%s/Library/Application Support/Dock/desktoppicture.db" % home

print "Opening desktop background database: '%s'" % desktopdb

# Make connection to existing db
conn = sqlite3.connect(desktopdb)
c = conn.cursor()

# Print current data
print "Current data:"
for row in c.execute('SELECT ROWID, value FROM data'):
    print row

# We're just going to update all rows. "value" == "filename" in the database.
# This could be more complex and randomly select backgrounds from a directory
# or whatever. But personally I want all my desktop backgrounds to be the same
# for all screens and desktops/spaces.
t = (background, )
c.execute("UPDATE data SET value=?", t)

conn.commit()

# Print updated data
print "Updated data:"
for row in c.execute('SELECT ROWID,value FROM data'):
    print row

conn.close()

# Force Dock to redraw all desktop backgrounds
os.system("Killall Dock")