I have container and python script that need to be run forever, for example:

import time    
if __name__ == "__main__":
    n = 0
    while True:
        print(f"Script is running! I want to see this string ! N is {n}")
        n += 1
        time.sleep(200)

So I

1. Enter to the virtual machine using mobaxterm
2. Enter to the container as docker exec -it -u root container_name bash
3. Run script inside container as python my_script.py
4. Script start working and I can see string which script prints in stdout...

5. Script is running! I want to see this string !

But session was interrupted, but the script still is running. What can I do to enter into the "script" to see the string/logs which it produces? How can I do it without interrupting the script? It needs to run forever inside the container.

解决方案

Make the script be the only thing the container does. For example, in your Dockerfile, make the default CMD be to run the script

FROM python:3.13
ENV PYTHONUNBUFFERED=1
WORKDIR /app
COPY my_script.py ./
CMD ["./my_script.py"]

And then you just run it. You don't need to "enter" anything or run any commands in interactive shells; just launch the container from the image.

docker build -t my-image .
docker run -d --name my-container my-image
docker logs -f my-container

The last line prints the logs from the container. If you stop it for whatever reason, the container is still running, and you can re-run docker logs to see the logs again.

Compare this setup to, for example, the standard postgres container: you don't normally start the container, get a shell, and then start the database; instead, you just run the container, and the only thing inside the container is the database server. docker exec is a useful debugging tool, but you shouldn't need it in normal use.