Docker exec and interactive mode explained: how to get inside containers

Docker's -it flag combines two options — -i for keeping standard input open and -t for allocating a pseudo-terminal — to create a functional shell session inside a container. When a container is launched with docker run -it, its lifecycle is tied to the main process, meaning the container stops as soon as that process exits. For background services like web servers or databases, detached mode (-d) runs the container without occupying the terminal. The docker exec command allows developers to run additional commands inside an already-running container without interrupting its main process. Unlike docker run, exiting a docker exec session leaves the container fully operational, making it the preferred tool for inspecting or debugging live environments.