Docker exec

What is Docker exec command?

The exec command is used to interact with already running containers on the Docker host. It allows you to start a session within the default directory of the container. Sessions created with the exec command are not restarted when the container is restarted.

Format

docker exec {Options} {Container Name} {Command} {Arguments}

Name of container

To find out the name of the container, you can run the ps command.

docker ps

For the sake of this shot, let’s assume the name/ID of the container is 123456789abc.

Starting bash

We can start bash-shell in an already running docker container using the following command:

docker exec -it 123456789abc bash 

Here, -it specifies that the bash-shell is going to be interactive, i.e., the user will be able to write commands and receive output. Moreover, if bash is not in the directory of the container, you need to specify the directory of bash at the end of the command.

Operating in a particular directory

If you want to run a command in a directory outside your container directory, you can use the option -w and specify the directory.

docker exec -w {path to directory} 123456789abc {command}

Multiple commands

To execute multiple commands in a single statement, the user needs to be careful of a couple of things:

• Use double quotation marks ("") instead of single quotation marks ( '' ).
• Use -c to read the command as a string.

docker exec 123456789abc bash -c "{command 1} ; {command 2}"

Visit herehttps://docs.docker.com/engine/reference/cli/docker/container/exec/ to read the official documentation.