import pywikibot
site = pywikibot.Site('en', 'wikipedia')  # The site we want to run our bot on
page = pywikibot.Page(site, 'Wikipedia:Sandbox')
page.text = page.text.replace('foo', 'bar')
page.save('Replacing "foo" with "bar"')  # Saves the page

import pywikibot
site = pywikibot.Site('wikipedia:en')
repo = site.data_repository()  # the Wikibase repository for given site
page = repo.page_from_repository('Q91')  # create a local page for the given item
item = pywikibot.ItemPage(repo, 'Q91')  # a repository item
data = item.get()  # get all item data from repository for this item

import pywikibot
from pywikibot import pagegenerators
from pywikibot.bot import ExistingPageBot

class MyBot(ExistingPageBot):

    update_options = {
        'text': 'This is a test text',
        'summary': 'Bot: a bot test edit with Pywikibot.'
    }

    def treat_page(self):
        """Load the given page, do some changes, and save it."""
        text = self.current_page.text
        text += '\n' + self.opt.text
        self.put_current(text, summary=self.opt.summary)

def main():
    """Parse command line arguments and invoke bot."""
    options = {}
    gen_factory = pagegenerators.GeneratorFactory()
    # Option parsing
    local_args = pywikibot.handle_args(args)  # global options
    local_args = gen_factory.handle_args(local_args)  # generators options
    for arg in local_args:
        opt, sep, value = arg.partition(':')
        if opt in ('-summary', '-text'):
            options[opt[1:]] = value
    MyBot(generator=gen_factory.getCombinedGenerator(), **options).run()

if __name == '__main__':
    main()