command: docker exec
short: Run a command in a running container
long: |-
  The `docker exec` command runs a new command in a running container.

  The command started using `docker exec` only runs while the container's primary
  process (`PID 1`) is running, and it is not restarted if the container is
  restarted.
usage: docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
pname: docker
plink: docker.yaml
options:
- option: detach
  shorthand: d
  default_value: "false"
  description: 'Detached mode: run command in the background'
- option: detach-keys
  description: Override the key sequence for detaching a container
- option: env
  shorthand: e
  description: Set environment variables
- option: interactive
  shorthand: i
  default_value: "false"
  description: Keep STDIN open even if not attached
- option: privileged
  default_value: "false"
  description: Give extended privileges to the command
- option: tty
  shorthand: t
  default_value: "false"
  description: Allocate a pseudo-TTY
- option: user
  shorthand: u
  description: 'Username or UID (format: <name|uid>[:<group|gid>])'
examples: |-
  ### Run `docker exec` on a running container

  First, start a container.

  ```bash
  $ docker run --name ubuntu_bash --rm -i -t ubuntu bash
  ```

  This will create a container named `ubuntu_bash` and start a Bash session.

  Next, execute a command on the container.

  ```bash
  $ docker exec -d ubuntu_bash touch /tmp/execWorks
  ```

  This will create a new file `/tmp/execWorks` inside the running container
  `ubuntu_bash`, in the background.

  Next, execute an interactive `bash` shell on the container.

  ```bash
  $ docker exec -it ubuntu_bash bash
  ```

  This will create a new Bash session in the container `ubuntu_bash`.

  ### Try to run `docker exec` on a paused container

  If the container is paused, then the `docker exec` command will fail with an error:

  ```bash
  $ docker pause test

  test

  $ docker ps

  CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                   PORTS               NAMES
  1ae3b36715d2        ubuntu:latest       "bash"              17 seconds ago      Up 16 seconds (Paused)                       test

  $ docker exec test ls

  FATA[0000] Error response from daemon: Container test is paused, unpause the container before exec

  $ echo $?
  1
  ```