$ jupyter notebook --help
The Jupyter HTML Notebook.

This launches a Tornado based HTML Notebook Server that serves up an
HTML5/Javascript Notebook client.

Subcommands
-----------

Subcommands are launched as `jupyter-notebook cmd [args]`. For information on
using subcommand 'cmd', do: `jupyter-notebook cmd -h`.

list
    List currently running notebook servers.
stop
    Stop currently running notebook server for a given port
password
    Set a password for the notebook server.

Options
-------
...

$ jupyter notebook list
Currently running servers:
http://localhost:8888/ :: /Users/myuser/dev/ipython-website
http://localhost:8889/ :: /Users/myuser