Display extra info on login screen

login_info.py

#!/usr/bin/python

import gtkhtml2
import gtk
import sys
import os
import atexit
import socket
from jinja2 import Template

def write_pid():
  filename="/var/run/login_info_{0}.pid".format(os.environ["DISPLAY"])
  pid = str(os.getpid())
  try:
    file(filename,'w+').write("{0}\n".format(pid))
    atexit.register(remove_pid, filename)
  except:
    print "Unable to create PID file", filename

def remove_pid(filename):
  try:
    os.remove(filename)
  except:
    print "Failed to remove", filename

def render(html):
  """
  Render the provided template, returning ready-to-display HTML.
  """
  template = Template(html)
  return template.render({
      "hostname": socket.gethostname(),
      "ip_address": socket.gethostbyname(socket.gethostname()),
      "kernel_version": os.uname()[2]})

def display(src="/var/lib/gdm/information.html"):
  doc = gtkhtml2.Document()
  doc.clear()
  try:
    f = open(src, "r")
  except OSError:
    print "failed to open"
    exit
  rendered_html = render(f.read())
  f.close()
  doc.open_stream(u'text/html')
  doc.write_stream(rendered_html)
  doc.close_stream()

  view = gtkhtml2.View()
  view.set_document(doc)
  window = gtk.Window()
  window.add(view)
  window.set_keep_above(True)
  window.set_gravity(gtk.gdk.GRAVITY_SOUTH_EAST)
  window.set_default_size(400, 150)

  window.set_decorated(False)
  window.show_all()
  width, height = window.get_size()
  window.move(gtk.gdk.screen_width() - width - 25, gtk.gdk.screen_height() - height - 50)
  gtk.main()

write_pid()
if len(sys.argv) > 1:
  display(sys.argv[1])
else:
  display()