a.py

#!/usr/bin/env python

#Copyright (c) 2013 rcmdnk

import os
import sys
import httplib2

from oauth2client.file import Storage
from oauth2client.tools import run
from oauth2client.client import OAuth2WebServerFlow
from apiclient.discovery import build

def main(uselist='',items=''):
    # Authentaation
    storage = Storage(os.path.expanduser('~/.gtask_oauth'))
    credentials = storage.get()

    if credentials is None or credentials.invalid:
        credentials = run(
            OAuth2WebServerFlow(
                client_id='326384869607-9c57sseqij1vpes16ect83irq490pn8c.apps.googleusercontent.com',
                client_secret='h0vi7XXzU3DRJyEa2aYFPRcm',
                scope=[
                    'https://www.googleapis.com/auth/tasks',
                    'https://www.googleapis.com/auth/tasks.readonly'],
                user_agent='gtaskslist/1.0',),
            storage)

    http = httplib2.Http()
    http = credentials.authorize(http)

    service = build('tasks', 'v1', http=http)

    # Get task lists
    tasklists = service.tasklists().list().execute()
    for tl in tasklists['items']:
        # Check list name
        if uselist != '' and tl['title'] != uselist:
            continue

        # Get tasks
        tasks = service.tasks().list(tasklist=tl['id']).execute()
        for t in tasks['items']:

            ttitle = t['title']
            if ttitle == '':
                continue
            useflag = 0
            if len(items) == 0 or items[0] == '':
                useflag = 1
            else:
                for i in items:
                    if ttitle.find(i) != -1:
                        useflag = 1
                        break
            if useflag == 1:
                print ttitle.encode('utf_8')

if __name__ == '__main__':
    # Get command line options
    from optparse import OptionParser
    usage = '''usage: %prog [-opts] arg1 arg2

       If arg1 arg2... are given, only tasks which include
       these words (ORed) will be listed (combined with -i)

       If you have not installed google-api-python-client, follow:
       https://developers.google.com/api-client-library/python/start/installation
       '''
    parser = OptionParser(usage)
    parser.add_option('-l', '--list', action='store',
                      dest='uselist', default='',
                      help='If \'USELIST\' is not an empty, tasks will be searched for only from the given list. [default: %default]')
    parser.add_option('-i', '--item', action='store',
                      dest='item', default='',
                      help='If \'ITEM\' is not an empty, only tasks which contains given item are listed up. Multiple words can be given by using \',\' as a separator. [default: %default]')
    (opts, args) = parser.parse_args()

    # Set parameters
    uselist = opts.uselist
    items = opts.item.split(',')
    for i in args:
        items.append(i)

    # Run main function
    main(uselist, items)