When is the `docker exec` command used?

The docker exec command is specifically designed for executing commands within the context of a running container. When you use this command, you can run any command as if you were inside the container's terminal, which is particularly useful for debugging, monitoring, or performing administrative tasks without needing to create a new container.

For example, if you need to access the shell of a container to inspect its filesystem, install packages, or troubleshoot an issue from inside the container, docker exec allows you to do that seamlessly. This capability is key for developers and system administrators who need to interact dynamically with their applications running in containers.

In contrast, the other options refer to functionalities that docker exec does not provide, such as removing containers, creating images, or listing commands. Each of those tasks requires different Docker commands that address their unique needs within container management.