# Persistent IPython notebooks in Windows

I’ve been using IPython for about six months, and I’ve grown to love the web-based notebook interface. It’s became my go-to environment when I want to do simple calculations, or test a new idea in Python. It’s also a lovely environment for literate programming, and I wish I’d had it for my university coursework.1

On my Mac, I’ve been using some scripts by Nathan Grigg to keep my IPython notebook server running continuously, and to give it a nicer hostname. Over the weekend, I realised that 1) IPython would be really useful at work, and 2) since my work computer is a PC, I need to adapt his scripts to work with Windows.

This post explains how to get a persistent IPython notebook on Windows. The ideas are based on Nathan’s post, but the implementation is a little different.

## Install IPython

I installed Python 3.42, then set up a virtualenv and installed IPython:

C:\Users\AWLC> C:\Python34\Scripts\virtualenv.exe ipython
C:\Users\AWLC> ipython\Scripts\activate.bat
(ipython) C:\Users\AWLC> pip install ipython


For some reason, this didn’t install all the notebook dependencies. I needed to install a few more modules:

(ipython) C:\Users\AWLC> pip install pyzmq jinja2 tornado jsonschema


Then I could start an IPython notebook server with ipython notebook, but I had to run that command myself, every time I logged in. Time to automate that step.

## Always running server with Task Scheduler

First I created a Batch script that started my IPython server:

C:\Users\AWLC\ipython\Scripts\ipython.exe notebook^
--no-browser^
--port=80^
--ip=127.0.0.13^
--notebook-dir=C:\Users\AWLC\Drive\Notebooks
PAUSE


Most of those options are fairly self-explanatory. The only line worth discussing is --ip, where I’ve used 127.0.0.13 instead of the conventional 127.0.0.1. In IPv4, the entire 127.0.0.0/8 address block is available for loopback. That means any 127.x.x.x address can act like a localhost address (at least on Windows; a little extra work is required to set this up on OS X).

Like Nathan, I have lots of processes serving to localhost, but I use different loopback addresses – rather than different ports – to keep them separate. I find this simpler than setting up Apache and configuring port forwarding.

Having created this script, now it needs to run whenever I log in. I created a new item in Task Scheduler with a “Start a program” action, and the following program:

cmd /c start "IPython notebook" /min "C:\Users\AWLC\bin\start_ipython.bat"


Here start_ipython.bat is the Batch script I wrote above. I also supply the /min flag, which auto-minimises the command window. I haven’t found a way to hide it entirely (at least not without giving the script admin permissions), but it’s better than nothing.

I also tweaked the task settings so that it auto-runs at login and tries to resume if the task fails.

So now I have an always-running IPython server at http://127.0.0.13. Finally, let’s give it a nicer hostname.

## Setting a virtual host

The hosts file in Windows lives at C:\Windows\System32\drivers\etc\hosts. After opening that (as an administrator), I added the following line:

127.0.0.13 py


The change took effect immediately: now py resolves to 127.0.0.13, and I can access my IPython server by going to py in my browser.

1. My second and third year coursework, called CATAM, was a mixture of programming and mathematics. We had to write programs for solving mathematical problems that were difficult to solve by hand. I wrote my programs in Python, and my writeup in LaTeX, because I needed to interleave program code and the underlying maths.</p><p>IPython notebooks allow you to intersperse Markdown, MathJax and code in an easy way. If you have to write something that combines maths and programming, I really suggest you give these notebooks a look. ↩︎

2. I’ve finally seen the light and switched to writing Python 3 for my new projects, after being stuck on Python 2 for years. There wasn’t a single big thing that persuaded me to change, just a growing collection of little “ooh, that looks nice” moments that pushed me over the edge. ↩︎