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- :title: First steps with Docker
- :description: Common usage and commands
- :keywords: Examples, Usage, basic commands, docker, documentation, examples
- First steps with Docker
- =======================
- Check your Docker install
- -------------------------
- This guide assumes you have a working installation of Docker. To check
- your Docker install, run the following command:
- .. code-block:: bash
- # Check that you have a working install
- docker info
- If you get ``docker: command not found`` or something like
- ``/var/lib/docker/repositories: permission denied`` you may have an incomplete
- docker installation or insufficient privileges to access Docker on your machine.
- Please refer to :ref:`installation_list` for installation instructions.
- Download a pre-built image
- --------------------------
- .. code-block:: bash
- # Download an ubuntu image
- sudo docker pull ubuntu
- This will find the ``ubuntu`` image by name in the :ref:`Central Index
- <searching_central_index>` and download it from the top-level Central
- Repository to a local image cache.
- .. NOTE:: When the image has successfully downloaded, you will see a
- 12 character hash ``539c0211cd76: Download complete`` which is the
- short form of the image ID. These short image IDs are the first 12
- characters of the full image ID - which can be found using ``docker
- inspect`` or ``docker images -notrunc=true``
- Running an interactive shell
- ----------------------------
- .. code-block:: bash
- # Run an interactive shell in the ubuntu image,
- # allocate a tty, attach stdin and stdout
- # To detach the tty without exiting the shell,
- # use the escape sequence Ctrl-p + Ctrl-q
- sudo docker run -i -t ubuntu /bin/bash
- .. _bind_docker:
- Bind Docker to another host/port or a Unix socket
- -------------------------------------------------
- .. warning:: Changing the default ``docker`` daemon binding to a TCP
- port or Unix *docker* user group will increase your security risks
- by allowing non-root users to potentially gain *root* access on the
- host (`e.g. #1369
- <https://github.com/dotcloud/docker/issues/1369>`_). Make sure you
- control access to ``docker``.
- With ``-H`` it is possible to make the Docker daemon to listen on a
- specific IP and port. By default, it will listen on
- ``unix:///var/run/docker.sock`` to allow only local connections by the
- *root* user. You *could* set it to ``0.0.0.0:4243`` or a specific host IP to
- give access to everybody, but that is **not recommended** because then
- it is trivial for someone to gain root access to the host where the
- daemon is running.
- Similarly, the Docker client can use ``-H`` to connect to a custom port.
- ``-H`` accepts host and port assignment in the following format:
- ``tcp://[host][:port]`` or ``unix://path``
- For example:
- * ``tcp://host:4243`` -> tcp connection on host:4243
- * ``unix://path/to/socket`` -> unix socket located at ``path/to/socket``
- ``-H``, when empty, will default to the same value as when no ``-H`` was passed in.
- ``-H`` also accepts short form for TCP bindings:
- ``host[:port]`` or ``:port``
- .. code-block:: bash
- # Run docker in daemon mode
- sudo <path to>/docker -H 0.0.0.0:5555 -d &
- # Download an ubuntu image
- sudo docker -H :5555 pull ubuntu
- You can use multiple ``-H``, for example, if you want to listen on
- both TCP and a Unix socket
- .. code-block:: bash
- # Run docker in daemon mode
- sudo <path to>/docker -H tcp://127.0.0.1:4243 -H unix:///var/run/docker.sock -d &
- # Download an ubuntu image, use default Unix socket
- sudo docker pull ubuntu
- # OR use the TCP port
- sudo docker -H tcp://127.0.0.1:4243 pull ubuntu
- Starting a long-running worker process
- --------------------------------------
- .. code-block:: bash
- # Start a very useful long-running process
- JOB=$(sudo docker run -d ubuntu /bin/sh -c "while true; do echo Hello world; sleep 1; done")
- # Collect the output of the job so far
- sudo docker logs $JOB
- # Kill the job
- sudo docker kill $JOB
- Listing all running containers
- ------------------------------
- .. code-block:: bash
- sudo docker ps
- Bind a service on a TCP port
- ------------------------------
- .. code-block:: bash
- # Bind port 4444 of this container, and tell netcat to listen on it
- JOB=$(sudo docker run -d -p 4444 ubuntu:12.10 /bin/nc -l 4444)
- # Which public port is NATed to my container?
- PORT=$(sudo docker port $JOB 4444 | awk -F: '{ print $2 }')
- # Connect to the public port
- echo hello world | nc 127.0.0.1 $PORT
- # Verify that the network connection worked
- echo "Daemon received: $(sudo docker logs $JOB)"
- Committing (saving) a container state
- -------------------------------------
- Save your containers state to a container image, so the state can be re-used.
- When you commit your container only the differences between the image the
- container was created from and the current state of the container will be
- stored (as a diff). See which images you already have using the ``docker
- images`` command.
- .. code-block:: bash
- # Commit your container to a new named image
- sudo docker commit <container_id> <some_name>
- # List your containers
- sudo docker images
- You now have a image state from which you can create new instances.
- Read more about :ref:`working_with_the_repository` or continue to the
- complete :ref:`cli`
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