使用SSH +屏幕远程启动IPython，然后分离并注销

Question

I have a computer on my LAN that I would like to run an IPython Notebook server on. The computer is headless, so I can only access this computer using SSH. I tried to start IPython Notebook through screen, then detach, but the kernel restarts with X server errors.

Specifically, I did the following:

• SSH into remote box: ssh -X 1.1.1.1
• Start or re-attach to last screen: screen -RD
• Start Notebook ipython notebook
• Detach and logout: ctrl-ad , exit

The remote Notebook server works fine, until I log out, and then try and create a matplotlib plot. At which time I get

Kernel Restarting
The kernel appears to have died. It will restart automatically.

from the client's web-browser, and

-c: cannot connect to X server localhost:10.0
2013-08-01 10:28:48.072 [NotebookApp] KernelRestarter: restarting kernel (1/5)
WARNING:root:kernel 6e0f5395-6ba7-44c8-912f-1e736dd66517 restarted

on the server.

It appears as though the Notebook can't plot as soon as I log out due to lack of X-resources. Does anyone have a solution to this?

Answer 1

Ipython is creating your plots (or any other X-graphics such as traitsui UI elements) in the X session you created with ssh -X . When you log out, the ssh tunnel closes along with that X session, thus the errors. Without the ssh tunnel, the plots have no way to get to you.

Assuming you don't have a physical terminal on the server with which to see the plots etc.., you can see matplotlib plots by telling IPython notebook to show the plots inline. Note that with the current version of ipython, the plots are static png's. I'm not sure if traitsui has a way to do something like that?

There's a few ways to do this:

• import the pylab module with %pylab inline
• import matplotlib with %matplotlib inline (not sure if this is available in older versions)
• run ipython with ipython notebook --pylab=inline
• configure ipython to use pylab inline always: run ipython profile create , then look for "inline" in ipython_notebook_config.py , which is in your ipython profile directory - ~/.config/ipython/profile_default/ on Ubuntu.

Answer 2

It appears as though these kernel restarts only occur when I import traitsui modules in a notebook. Specially, the following imports cause the error.

from traitsui.api import *
from traitsui.menu import *

The solution is to change the backend for traitsui, before importing any traitsui modules,

from traits.etsconfig.api import ETSConfig
ETSConfig.toolkit = 'null'

EDIT: the traitsui functionality was not being used across ssh, it was just part of a larger module.

Answer 3

• SSH into remote box: ssh -X 1.1.1.1
• Start screen: screen -S ipython_process
• Start Notebook: ipython notebook --profile=nbserver
• Detach: ctrl-ad

Enjoy remotely via browser on port 8888