page_title: First steps with Docker page_description: Common usage and commands page_keywords: Examples, Usage, basic commands, docker, documentation, examples
This guide assumes you have a working installation of Docker. To check your Docker install, run the following command:
# 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 Installation for installation instructions.
# Download an ubuntu image $ sudo docker pull ubuntu
This will find the ubuntu
image by name on Docker Hub and download it from Docker Hub 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 usingdocker inspect
ordocker images --no-trunc=true
If you're using OS X then you shouldn't use sudo
.
# 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 # note: This will continue to exist in a stopped state once exited (see "docker ps -a") $ sudo docker run -i -t ubuntu /bin/bash
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 gain root access on the host. Make sure you control access todocker
. If you are binding to a TCP port, anyone with access to that port has full Docker access; so it is not advisable on an open network.
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 0.0.0.0:2375
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:2375
-> TCP connection on host:2375unix://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
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
# Run docker in daemon mode $ sudo <path to>/docker -H tcp://127.0.0.1:2375 -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://127.0.0.1:2375 pull ubuntu
# 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
$ sudo docker ps # Lists only running containers $ sudo docker ps -a # Lists all containers
# Start a new container $ JOB=$(sudo docker run -d ubuntu /bin/sh -c "while true; do echo Hello world; sleep 1; done") # Stop the container $ docker stop $JOB # Start the container $ docker start $JOB # Restart the container $ docker restart $JOB # SIGKILL a container $ docker kill $JOB # Remove a container $ docker stop $JOB # Container must be stopped to remove it $ docker rm $JOB
# 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)"
Save your containers state to an 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.
# Commit your container to a new named image $ sudo docker commit <container_id> <some_name> # List your containers $ sudo docker images
You now have an image state from which you can create new instances.
Read more about Share Images via Repositories or continue to the complete Command Line