Timemachine script to mount TimeMachine backup disk and trigger a time machine backup.Had to make some modifications to put in in the OSX standard log location.Reference:http://hints.macworld.com/article.php?story=20100712085231232

gistfile1.py

#!/usr/bin/env python

# place in /etc/periodic/daily to run nightly (or hourly if set up):
#
#   sudo cp -f timemachine.py /etc/periodic/daily/667.timemachine
#   sudo cp -f timemachine.py /etc/periodic/hourly/667.timemachine

import re
import datetime
import time
from subprocess import Popen, PIPE

# do executes a shell command, returning stdout and stderr

def do(cmd):
  p = Popen(cmd, shell=True, stdin=PIPE, stdout=PIPE, stderr=PIPE)
  (fi, fo, fe) = (p.stdin, p.stdout, p.stderr)
  fi.close()
  msg = fo.read()
  fo.close()
  fe.close()
  return msg

# mounted checks if vol is mounted

def mounted(vol):
  pat = r'/Volumes/(\S+)\s+[(](.+)[)]'
  msg = do('/sbin/mount')
  vols = dict(re.compile(pat).findall(msg))
  return vol in vols.keys()

# disks returns a dictionary associating e.g. 'Flash' to 'disk0s2'

def disks():
  pat = r'Apple_HFS\s+(\S+)\s+.+(disk\d+s\d+)'
  msg = do('/usr/sbin/diskutil list')
  vols = re.compile(pat).findall(msg)
  return dict(vols)

# sleep waits a bit

def sleep():
  time.sleep(30)

# mount_volume returns pair (now mounted?, was mounted?),
# after attempting to mount volume for "name" as needed

def mount_volume(vol, logfile):
  if mounted(vol):
    (now, was) = (True, True)
  else:
    was = False
    diskID = disks()
    mountable = diskID.keys()
    if vol in mountable:
      do("/usr/sbin/diskutil mount %s >>'%s' 2>&1" % (diskID[vol], logfile))
      sleep()
    now = mounted(vol)
  return (now, was)

# unmount_volume unmounts volume

def unmount_volume(vol, logfile):
  do("/usr/sbin/diskutil unmount '/Volumes/%s' >>'%s' 2>&1" % (vol, logfile))

# run Time Machine
# Time Machine has finished when 'backupd' is no longer running

logdir = '/Library/Logs/Backup Logs'
backupd = "/System/Library/CoreServices/backupd.bundle/Contents/Resources/backupd-helper >>'%s' 2>&1"

def start_backupd(logfile):
  do("echo 'starting Time Machine' >>'%s'" % logfile)
  do(backupd % logfile)

def backupd_running(logfile):
  return do("ps -ax | grep [b]ackupd >>'%s' 2>&1" % logfile)

def timemachine(vol):
  now = datetime.datetime.now().strftime("%F %H-%M-%S")
  logfile = "%s/%s (Time Machine)" % (logdir, now)
  (tnow, twas) = mount_volume(vol, logfile)
  if tnow:
    start_backupd(logfile)
    sleep()
    while backupd_running(logfile):
      sleep()
    if not twas:
      sleep()
      for i in range(1,8):
        sleep()
        unmount_volume(vol, logfile)
        if not mounted(vol):
          break

# execute (replace 'Time' by name of Time Machine volume)

timemachine('TimeMachine')