How do I send text messages to the notification bubbles?

We can always call notify-send as a subprocess, e.g like that:

#!/usr/bin/env python
#-*- coding: utf-8 -*-

import subprocess

def sendmessage(message):
    subprocess.Popen(['notify-send', message])
    return

Alternatively we could also install python-notify2 or python3-notify2 and call the notification through that:

import notify2

def sendmessage(title, message):
    notify2.init("Test")
    notice = notify2.Notification(title, message)
    notice.show()
    return

python3

Whilst you can call notify-send via os.system or subprocess it is arguably more consistent with GTK3 based programming to use the Notify gobject-introspection class.

A small example will show this in action:

from gi.repository import GObject
from gi.repository import Notify

class MyClass(GObject.Object):
    def __init__(self):

        super(MyClass, self).__init__()
        # lets initialise with the application name
        Notify.init("myapp_name")

    def send_notification(self, title, text, file_path_to_icon=""):

        n = Notify.Notification.new(title, text, file_path_to_icon)
        n.show()

my = MyClass()
my.send_notification("this is a title", "this is some text")

To answer Mehul Mohan question as well as propose the shortest way to push a notification with title and message sections:

import os
os.system('notify-send "TITLE" "MESSAGE"')

Putting this in function might be a bit confusing due to quotes in quotes

import os
def message(title, message):
  os.system('notify-send "'+title+'" "'+message+'"')

You should use notify2 package, it is a replacement for python-notify. Use it as followed.

pip install notify2

And the code:

import notify2
notify2.init('app name')
n = notify2.Notification('title', 'message')
n.show()

import os
mstr='Hello'
os.system('notify-send '+mstr)

For anyone looking at this in +2018, I can recommend the notify2 package.

This is a pure-python replacement for notify-python, using python-dbus to communicate with the notifications server directly. It’s compatible with Python 2 and 3, and its callbacks can work with Gtk 3 or Qt 4 applications.

PyNotify2, suggested by many answers, considers itself as deprecated as of late 2020:

notify2 is - or was - a package to display desktop notifications on Linux. Those are the little bubbles which tell a user about e.g. new emails.

notify2 is deprecated. Here are some alternatives:

• desktop_notify is a newer module doing essentially the same thing.
• If you’re writing a GTK application, you may want to use GNotification (intro, Python API).
• For simple cases, you can run notify-send as a subprocess. The py-notifier package provides a simple Python API around this, and can also display notifications on Windows.

So, given the above suggestions:

• The notify-send subprocess approach is already explained in other answers, and py-notifier can simplify that, with an added bonus of working on Windows platforms using win10toast, but also with all the drawbacks of a subprocess call under the hood:

from pynotifier import Notification

Notification(
    title='Notification Title',
    description='Notification Description',
    icon_path='path/to/image/file/icon.png',
    duration=5,
    urgency=Notification.URGENCY_CRITICAL
).send()

• desktop_notify seems to use DBus directly, just like PyNotify2, and has dbus-next as its sole dependency.

notify = desktop_notify.aio.Notify('summary', 'body')
await notify.show()

• fossfreedom's answer covers GTK's gi introspection route. But please note he uses a different API than the one mentioned above:
  • There's the Gio.Notification API, from Gio 2.4 onwards, mentioned by pynotify2
  • And there's the Notify API, from GLib 2.0 onwards, used in @fossfreedom's code snippet.