I created a virtual environment in python3 (with venv) to use several packages, including jupyter notebook.
Running the bash command jupyter --config-dir I noticed that the config file used by jupyter notebook in the virtual environment is the main one of my machine (~/.jupyter/jupyter_notebook_config.py).
How can I create a new config file and tell the virtual environment to use it. The goal is not to modify the main one because I need it for other projects.
from https://jupyter.readthedocs.io/en/latest/use/jupyter-directories.html:
Config files are stored by default in the ~/.jupyter directory.
JUPYTER_CONFIG_DIR
Set this environment variable to use a particular directory, other than the default, for Jupyter config files.
So what you'd need to do is set the JUPYTER_CONFIG_DIR environment variable when activating the environment.
How you do this depends on what virtual environment manager you're using. I believe with venv you should be able to add
export JUPYTER_CONFIG_DIR=/your/custom/config/dir
to the activate script that runs when you activate your virtual environment (should be in $venv/environmentname/bin/activate).
Another option that you might prefer (which is the route I went for this since I'm using pyenv+virtualenv, which does not use the activate script), you can use an additional tool like direnv or dotenv to set environment variables by project. In the case of direnv (which is a little simpler IMO), you create a .envrc file in your project directory with the export command from above, and then every time you cd into your project directory it runs the commands in the .envrc file. This works well if your virtual environments are organized by project.
Once the JUPYTER_CONFIG_DIR environment variable is being set properly, after your environment activates when you run jupyter notebook --generate-config it should create a new config file in the new directory.