Start IPython kernel from within Python script

Question

Say I have the following file t.py:

from IPython import get_ipython

if __name__ == '__main__':
    ip = get_ipython()
    if ip is not None:
        print('Found IPython')

Here's what happens if I run it, with both Python and IPython:

% python t.py
% ipython t.py 
Found IPython

Note that, only when running it with ipython, is get_ipython() not None.

Is there a way to start an IPython kernel from within the script, so that even if I run it as python t.py, then get_ipython() will not be None?

yes, and got ``` warn("The IPython.kernel package has been deprecated since IPython 4.0." NOTE: When using the ipython kernel entry point, Ctrl-C will not work. To exit, you will have to explicitly quit this process, by either sending "quit" from a client, or using Ctrl-\ in UNIX-like environments. To read more about this, see github.com/ipython/ipython/issues/2049 To connect another client to this kernel, use: --existing kernel-15293.json ``` — ignoring_gravity
– ignoring_gravity, Commented Jun 21, 2021 at 18:30

paiv · Accepted Answer · 2021-06-30 19:21:21Z

4

+100

IPython starts new interactive shell, i.e. your code will be suspended until IPython shell is terminated.

You can have a launcher in a separate file, launcher.py:

import IPython

if __name__ == '__main__':
    IPython.start_ipython(['t.py'])

% python launcher.py
Found IPython

For other options of embedding IPython see the docs https://ipython.readthedocs.io/en/stable/interactive/reference.html#embedding-ipython

answered Jun 30, 2021 at 19:21

paiv

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4 Comments

ignoring_gravity Over a year ago

Thanks! I have a question though - suppose t.py ends with sys.exit(1). Then, running python t.py will work without exceptions, and the return code will be 1, while python launcher.py will through a SystemExit error and show a traceback. Could launcher.py preserve the exit code of t.py?

paiv Over a year ago

@ignoring_gravity You can capture SystemExit exception which has code value, then sys.exit with that value.

ignoring_gravity Over a year ago

Do you mean to put that in launcher.py? I've tried, and it's not working for me

paiv Over a year ago

Yes, you can capture SystemExit and return its code in launcher.py, but t.py will still print stack trace.

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