notify when execution/command is completed

With the newest version of iTerm, you can use the alert on next mark functionality of the shell integration.

Finally someone created a nice library for it.

You just install it:

pip install jupyternotify

Import it in your notebook:

import jupyternotify
ip = get_ipython()
ip.register_magics(jupyternotify.JupyterNotifyMagics)

and use a magic command:

%%notify
import time
time.sleep(5)

and get a nice notification:

Git-page also shows how to load it automatically.

Are you using IPython Notebook, or IPython from the terminal? If you are using IPython Notebook, I suggest using the notify extension available from https://github.com/sjpfenninger/ipython-extensions (write up available here)