UPDATE
You can now just run jupyter notebook list
in the terminal to get the running jupyter sessions with tokens.
Take care that you are within the right environment (conda, virtualenv etc.) otherwise the sessions will list without the associated tokens. Eg: The above reference screenshot is from the conda environment.
Old answer:
Run ipython and enter the following:
> ipython
[1] : system("jupyter" "notebook" "list")
Out[1]:
['Currently running servers:','http://localhost:8895/token=067470c5ddsadc54153ghfjd817d15b5d5f5341e56b0dsad78a :: /u/user/dir']
If the notebook is running on a remote server, you will have to login in to that server first before running ipython.