The Docker container is launched via a Compose file, there is no Dockerfile itself. The container has /bin/bash, it starts and crashes due to a syntax error. How to debug the cause?

To debug the cause of a container crash due to a syntax error, you can do the following:

1. Run the container in interactive mode with access to bash to manually check the environment:

docker-compose run --rm <service_name> /bin/bash

2. If the container crashes immediately, try changing the startup command in docker-compose.yml to something simple, like sleep infinity, so the container remains running.

3. After starting the container, enter it and check the scripts or commands executed at startup. The error might be in the entrypoint or CMD.

4. View the container logs:

docker-compose logs <service_name>

5. If you suspect a shell script error, check its syntax with bash -n <script>.

6. If necessary, temporarily replace the startup command with bash and manually execute steps to localize the error.

This approach will help find and fix the syntax error, even if the original Dockerfile is not available.