docker-exec

View documentation for the original command

$ tldr docker container exec

docker exec [OPTIONS] CONTAINER COMMAND [ARG...]

-d, --detach
    Run command in background of the container

--detach-keys
    Select escape sequence for detaching a container

-e, --env =
    Set environment variables

--env-file
    Read in a file of environment variables

-i, --interactive
    Keep STDIN open even if not attached

--privileged
    Give extended privileges to this command

-t, --tty
    Allocate a pseudo-TTY

-u, --user [:]
    Username or UID (format: <user>[:<group>] or <UID>[:<GID>])

-w, --workdir
    Working directory inside the container

The docker exec command allows users to run arbitrary commands inside a running Docker container without stopping or restarting it. This is essential for debugging, maintenance, and interactive sessions in containerized environments.

It attaches to the container's process namespace, executing the specified command as a child process of the container's PID 1. Common use cases include checking logs with /bin/sh, installing packages, or running scripts.

For interactive shells, combine -it flags to allocate a TTY and keep STDIN open, mimicking a native shell experience. Non-interactive commands run detached with -d.

Security is managed via --user to specify run-as user/group, preventing root escalation. Environment variables can be passed with -e or files via --env-file. The container must be running; use docker ps to verify.

This command enhances DevOps workflows by enabling live inspections, configuration tweaks, and troubleshooting in production-like setups, promoting immutable infrastructure principles.

Container must be running (docker start if stopped). No support for stopped/exited containers. Privileged mode poses security risks. Interactive mode requires proper terminal setup.

docker exec -it <container> /bin/bash for interactive shell.
docker exec <container> ls /app to list files.

Introduced in Docker 1.3.0 (2014) to address limitations of docker run for running containers. Evolved with Docker Engine; key enhancements in 17.06 for better security and multi-platform support.

docker(1), docker-run(1), docker-attach(1), docker-start(1)