The short answer

To start an interactive Bash shell in a Docker container, you can use the [.inline-code]docker exec[.inline-code] command that allows developers to execute commands in running containers.

 $ docker exec -it <container> bash

Where [.inline-code]container[.inline-code] is either the name or the identifier of a Docker container that can be obtained using the [.inline-code]docker ps[.inline-code] command.

[#easily-recall-syntax]Use Warp's Workflows feature to easily recall the syntax[#easily-recall-syntax]

If you’re using Warp as your terminal and you need to quickly retrieve this command, you can use Warp's Workflows feature by pressing [.inline-code]CTRL-SHIFT-R[.inline-code], typing [.inline-code]start bash docker[.inline-code], then pressing [.inline-code]ENTER[.inline-code] to use the suggested command:

[#bash-shell-on-container]Running a Bash shell on container startup[#bash-shell-on-container]

To start a Docker container with an interactive Bash shell, you can combine the [.inline-code]-i[.inline-code] flag (short for interactive) and the [.inline-code]-t[.inline-code] flag (short for TTY) of the [.inline-code]docker run[.inline-code] command, which instructs Docker to allocate a pseudo-TTY connected to the container’s standard input (i.e. stdin).

 $ docker run -it <image> bash

Where [.inline-code]image[.inline-code] is the name of the image you want to start a container from.

[#sh-and-others]Running [.inline-code]sh[.inline-code] and other shells[#sh-and-others]

Most images usually come pre-packaged with several shell binaries such as [.inline-code]sh[.inline-code], [.inline-code]csh[.inline-code], etc. To start a Docker container with an interactive shell other than Bash, simply replace the [.inline-code]command[.inline-code] argument by the shell you want to use when running the [.inline-code]docker run[.inline-code] command.

 $ docker run -it <image> /bin/sh

[#override-entrypoint]Overriding the entrypoint[#override-entrypoint]

Some Docker images may include an [.inline-code]ENTRYPOINT[.inline-code] instruction that specifies which command to run when the container is started.

For example, if the Docker image has the following [.inline-code]ENTRYPOINT[.inline-code]:

 ENTRYPOINT ['node', 'app.js']

Then, by default, the container will start by running the [.inline-code]node app.js[.inline-code] command.

To override this entry point and start the container with a Bash shell instead of the default command, you can use the [.inline-code]--entrypoint[.inline-code] flag as follows:

 $ docker run --entrypoint /bin/bash -it <image>

[#run-single-command]Running a single command in a container with Bash[#run-single-command]

It may happen that you need to run a single command in a running Docker container. Instead of starting an interactive shell session, you can use the [.inline-code]-c[.inline-code] flag (short for command) of the [.inline-code]bash[.inline-code] utility which will execute the specified command.

 $ docker exec <container> /bin/bash -c '<command>'

Where:

• [.inline-code]container[.inline-code] is either the name or the identifier of a container.
• [.inline-code]command[.inline-code] is the command you want to run in the container.

For example, to restart a running service:

 $ docker exec ab4fb7dd8ffa /bin/bash -c 'service ssh restart'

If you want to learn how to execute entire scripts instead of single commands, you can read our other article on how to run a shell script using a Dockerfile.

[#bash-as-container]Running Bash as a container[#bash-as-container]

If you want to run the Bash shell as a standalone container to test new features of more recent versions or test shell scripts against different Bash versions to ensure compatibility, you can use the official [.inline-code]bash[.inline-code] image available on Docker hub.

 $ docker run -it bash

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