Opening a shell in container in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What command lets you open an interactive shell inside a running Docker container?

Use docker exec -it <container_name_or_id> /bin/bash to open an interactive bash shell inside a running container.

beginner

What does the -it option mean in docker exec -it?

-i means interactive mode to keep STDIN open, and -t allocates a pseudo-TTY so you get a terminal interface.

beginner

How do you open a shell in a container that uses sh instead of bash?

Use docker exec -it <container> /bin/sh because some containers have only sh shell.

intermediate

What is the difference between docker exec and docker attach?

docker exec runs a new command (like a shell) inside the container, while docker attach connects to the main process's input/output of the container.

beginner

Why might you want to open a shell inside a running container?

To inspect the container's file system, debug running processes, or manually run commands inside the container environment.

Which command opens an interactive bash shell inside a running Docker container named 'webapp'?

A docker run -it webapp /bin/bash

B docker exec -it webapp /bin/bash

C docker start -it webapp /bin/bash

D docker attach webapp /bin/bash

Use docker exec -it webapp /bin/bash to open a new interactive shell inside the running container.

What does the -t option do in the command docker exec -it?

A Runs the container in detached mode

B Stops the container after command finishes

C Specifies the target container

D Allocates a pseudo-TTY for terminal interface

-t allocates a pseudo-terminal so you get a terminal interface.

If a container does not have bash installed, which shell is commonly available?

A /bin/sh

B /bin/zsh

C /bin/fish

D /bin/csh

Most containers have /bin/sh as a minimal shell.

Which command connects to the main process's input/output of a running container?

A docker attach

B docker exec

C docker run

D docker shell

docker attach connects to the main process's input/output streams.

Why is opening a shell inside a container useful?

A To permanently change container settings

B To delete the container

C To inspect and debug the container environment

D To update Docker software

Opening a shell helps inspect files and debug inside the container.

Explain how to open an interactive shell inside a running Docker container and why you might do this.

Think about the command and the purpose of opening a shell.

Describe the difference between docker exec and docker attach commands.

Consider how each command interacts with the container.