Run python script using existing ipython kernel without console

Question

I can run a python script from a bash shell like so:

>> python script.py

I can also start an iPython kernel and connect multiple iPython consoles to the same kernel like so:

>> ipython kernel
...
To connect another client to this kernel, use:
--existing kernel-8987.json

then, for as many consoles as I would like, I execute

>> jupyter console --existing kernel-8987.json

However, what I would like to do is start a kernel, but then run scripts without opening a console. I'd like to do something like this:

>> ipython --existing kernel-8987.json script.py

Is this possible to do this somehow?

user202729 · Accepted Answer · 2021-12-07 03:15:13Z

5

Extending on the other answer and use the %run magic command¹, it's possible to do this (which works for multiple-line scripts):

$ jupyter console --simple-prompt --existing kernel-8987.json <<< '%run script.py'

or (on Windows where <<< doesn't work)

> echo %run script.py | jupyter console --simple-prompt --existing kernel-8987.json

Unfortunately, this method still prints some redundant prompt (In[1]:) on the console.

Alternatively, using Python API: (create a script to execute this Python code) (on my machine, this method is much faster)

from jupyter_client.manager import KernelManager
manager=KernelManager(connection_file="full path to connection file.json")
manager.load_connection_file()
manager.client().execute("commands to execute")

The commands to execute might span multiple lines, or have the form %run file.py.

There's also silent=True, store_history=False as parameters to execute().

The full path to the connection file can be found as

Path(jupyter_core.paths.jupyter_runtime_dir()) / "kernel-8987.json", or
jupyter_client.connect.find_connection_file("kernel-8987.json") (find file with specific name), or
jupyter_client.connect.find_connection_file() (find the latest file)

See also jupyter-client documentation.

Disclaimer: Some of the code are taken from jupyter-vim plugin, and manager.load_connection_file and connect.find_connection_file appears to be undocumented.

¹: As mentioned in the documentation, the file is executed in a new namespace unless you use -i.

edited Dec 7, 2021 at 3:15

answered Aug 13, 2021 at 9:34

user202729

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1 Comment

overflo Over a year ago

You can use connection_file = jupyter_client.connect.find_connection_file() if you don't want to provide a path to the kernel file and would like your script to work as if --existing has been passed in the command line

paiv · Accepted Answer · 2021-03-15 12:35:27Z

4

+50

% jupyter console --version
6.2.0

I can exec one-liners from a file like this:

% jupyter console --simple-prompt --existing kernel-8987.json < script.py

edited Mar 15, 2021 at 12:35

answered Mar 14, 2021 at 22:13

paiv

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3 Comments

Arroz con Tomate Over a year ago

kernel-21247 is the kernel name or the .json file name?

paiv Over a year ago

@ArrozconTomate the json file is the moniker for the kernel, as described in the question. I've update to show where the script.py goes. But still note it would only accept complete one line statements, not nested blocks. At least not in the version I've tested.

Arroz con Tomate Over a year ago

How did you get the .json file? Simply by using 'jupyter kernelspec list' and browsing in the corresponding file location? or is there another way to do it?

mrclary · Accepted Answer · 2022-05-07 01:55:55Z

4

It seems that jupyter has this functionality already built in.

$ jupyter run --existing kernel-8987.json script.py

I don't know if this was a feature addition since the OP, or if I was really stupid and didn't RTFM.

$ jupyter run --help
Run Jupyter kernel code.

Options
=======
...
--existing=<CUnicode>
    Connect to an already running kernel
    Default: ''
    Equivalent to: [--JupyterConsoleApp.existing]

The other answers will run the code in the existing kernel, but still open a console in the process. The run subcommand does exactly what I requested: runs the code without opening an interactive console.

answered May 7, 2022 at 1:55

mrclary

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user202729 Over a year ago

Looks like jupyter run was first added in Aug 8, 2016 in version 5.0.0. Add jupyter-run command to jupyter_client collection · jupyter/jupyter_client@08d6c30 // my answer using Python API does not open a new console though.

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