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@@ -24,147 +24,131 @@ Running an application inside a container takes a single command: `docker run`.
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## Run a Hello world
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## Run a Hello world
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-Let's try it now.
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+Let's run a hello world container.
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$ docker run ubuntu /bin/echo 'Hello world'
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$ docker run ubuntu /bin/echo 'Hello world'
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Hello world
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Hello world
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-And you just launched your first container!
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+You just launched your first container!
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-So what just happened? Let's step through what the `docker run` command
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-did.
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+In this example:
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-First we specified the `docker` binary and the command we wanted to
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-execute, `run`. The `docker run` combination *runs* containers.
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+* `docker run` runs a container.
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-Next we specified an image: `ubuntu`. This is the source of the container
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-we ran. Docker calls this an image. In this case we used the Ubuntu
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-operating system image.
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+* `ubuntu` is the image you run, for example the Ubuntu operating system image.
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+ When you specify an image, Docker looks first for the image on your
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+ Docker host. If the image does not exist locally, then the image is pulled from the public
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+ image registry [Docker Hub](https://hub.docker.com).
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-When you specify an image, Docker looks first for the image on your
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-Docker host. If it can't find it then it downloads the image from the public
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-image registry: [Docker Hub](https://hub.docker.com).
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+* `/bin/echo` is the command to run inside the new container.
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-Next we told Docker what command to run inside our new container:
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-
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- /bin/echo 'Hello world'
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-
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-When our container was launched Docker created a new Ubuntu
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-environment and then executed the `/bin/echo` command inside it. We saw
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-the result on the command line:
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+The container launches. Docker creates a new Ubuntu
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+environment and executes the `/bin/echo` command inside it and then prints out:
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Hello world
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Hello world
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-So what happened to our container after that? Well Docker containers
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-only run as long as the command you specify is active. Here, as soon as
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-`Hello world` was echoed, the container stopped.
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+So what happened to the container after that? Well, Docker containers
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+only run as long as the command you specify is active. Therefore, in the above example,
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+the container stops once the command is executed.
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-## An interactive container
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+## Run an interactive container
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-Let's try the `docker run` command again, this time specifying a new
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-command to run in our container.
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+Let's specify a new command to run in the container.
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$ docker run -t -i ubuntu /bin/bash
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$ docker run -t -i ubuntu /bin/bash
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root@af8bae53bdd3:/#
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root@af8bae53bdd3:/#
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-Here we've again specified the `docker run` command and launched an
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-`ubuntu` image. But we've also passed in two flags: `-t` and `-i`.
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-The `-t` flag assigns a pseudo-tty or terminal inside our new container
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-and the `-i` flag allows us to make an interactive connection by
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-grabbing the standard in (`STDIN`) of the container.
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+In this example:
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-We've also specified a new command for our container to run:
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-`/bin/bash`. This will launch a Bash shell inside our container.
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+* `docker run` runs a container.
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+* `ubuntu` is the image you would like to run.
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+* `-t` flag assigns a pseudo-tty or terminal inside the new container.
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+* `-i` flag allows you to make an interactive connection by
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+grabbing the standard in (`STDIN`) of the container.
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+* `/bin/bash` launches a Bash shell inside our container.
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-So now when our container is launched we can see that we've got a
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+The container launches. We can see there is a
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command prompt inside it:
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command prompt inside it:
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root@af8bae53bdd3:/#
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root@af8bae53bdd3:/#
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-Let's try running some commands inside our container:
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+Let's try running some commands inside the container:
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root@af8bae53bdd3:/# pwd
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root@af8bae53bdd3:/# pwd
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/
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/
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root@af8bae53bdd3:/# ls
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root@af8bae53bdd3:/# ls
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bin boot dev etc home lib lib64 media mnt opt proc root run sbin srv sys tmp usr var
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bin boot dev etc home lib lib64 media mnt opt proc root run sbin srv sys tmp usr var
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-You can see we've run the `pwd` to show our current directory and can
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-see we're in the `/` root directory. We've also done a directory listing
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-of the root directory which shows us what looks like a typical Linux
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-file system.
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+In this example:
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-You can play around inside this container and when you're done you can
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-use the `exit` command or enter Ctrl-D to finish.
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+* `pwd` displays the current directory, the `/` root directory.
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+* `ls` displays the directory listing of the root directory of a typical Linux file system.
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- root@af8bae53bdd3:/# exit
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+Now, you can play around inside this container. When completed, run the `exit` command or enter Ctrl-D
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+to exit the interactive shell.
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-As with our previous container, once the Bash shell process has
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-finished, the container is stopped.
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+ root@af8bae53bdd3:/# exit
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-## A daemonized Hello world
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+>**Note:** As with our previous container, once the Bash shell process has
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+finished, the container stops.
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-Now a container that runs a command and then exits has some uses but
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-it's not overly helpful. Let's create a container that runs as a daemon,
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-like most of the applications we're probably going to run with Docker.
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+## Start a daemonized Hello world
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-Again we can do this with the `docker run` command:
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+Let's create a container that runs as a daemon.
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$ docker run -d ubuntu /bin/sh -c "while true; do echo hello world; sleep 1; done"
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$ docker run -d ubuntu /bin/sh -c "while true; do echo hello world; sleep 1; done"
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1e5535038e285177d5214659a068137486f96ee5c2e85a4ac52dc83f2ebe4147
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1e5535038e285177d5214659a068137486f96ee5c2e85a4ac52dc83f2ebe4147
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-Wait, what? Where's our "hello world" output? Let's look at what we've run here.
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-It should look pretty familiar. We ran `docker run` but this time we
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-specified a flag: `-d`. The `-d` flag tells Docker to run the container
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-and put it in the background, to daemonize it.
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+In this example:
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-We also specified the same image: `ubuntu`.
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+* `docker run` runs the container.
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+* `-d` flag runs the container in the background (to daemonize it).
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+* `ubuntu` is the image you would like to run.
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-Finally, we specified a command to run:
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+Finally, we specify a command to run:
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/bin/sh -c "while true; do echo hello world; sleep 1; done"
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/bin/sh -c "while true; do echo hello world; sleep 1; done"
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-This is the (hello) world's silliest daemon: a shell script that echoes
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-`hello world` forever.
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-So why aren't we seeing any `hello world`'s? Instead Docker has returned
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-a really long string:
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+In the output, we do not see `hello world` but a long string:
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1e5535038e285177d5214659a068137486f96ee5c2e85a4ac52dc83f2ebe4147
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1e5535038e285177d5214659a068137486f96ee5c2e85a4ac52dc83f2ebe4147
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-This really long string is called a *container ID*. It uniquely
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+This long string is called a *container ID*. It uniquely
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identifies a container so we can work with it.
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identifies a container so we can work with it.
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> **Note:**
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> **Note:**
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-> The container ID is a bit long and unwieldy. A bit later,
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-> we'll see a shorter ID and ways to name our containers to make
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+> The container ID is a bit long and unwieldy. Later, we will cover the short
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+> ID and ways to name our containers to make
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> working with them easier.
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> working with them easier.
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We can use this container ID to see what's happening with our `hello world` daemon.
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We can use this container ID to see what's happening with our `hello world` daemon.
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-Firstly let's make sure our container is running. We can
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-do that with the `docker ps` command. The `docker ps` command queries
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-the Docker daemon for information about all the containers it knows
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+First, let's make sure our container is running. Run the `docker ps` command.
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+The `docker ps` command queries the Docker daemon for information about all the containers it knows
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about.
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about.
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$ docker ps
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$ docker ps
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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1e5535038e28 ubuntu /bin/sh -c 'while tr 2 minutes ago Up 1 minute insane_babbage
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1e5535038e28 ubuntu /bin/sh -c 'while tr 2 minutes ago Up 1 minute insane_babbage
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-Here we can see our daemonized container. The `docker ps` has returned some useful
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-information about it, starting with a shorter variant of its container ID:
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-`1e5535038e28`.
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+In this example, we can see our daemonized container. The `docker ps` returns some useful
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+information:
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+
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+* `1e5535038e28` is the shorter variant of the container ID.
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+* `ubuntu` is the used image.
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+* the command, status, and assigned name `insane_babbage`.
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-We can also see the image we used to build it, `ubuntu`, the command it
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-is running, its status and an automatically assigned name,
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-`insane_babbage`.
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> **Note:**
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> **Note:**
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> Docker automatically generates names for any containers started.
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> Docker automatically generates names for any containers started.
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> We'll see how to specify your own names a bit later.
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> We'll see how to specify your own names a bit later.
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-Okay, so we now know it's running. But is it doing what we asked it to do? To
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+Now, we know the container is running. But is it doing what we asked it to do? To
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see this we're going to look inside the container using the `docker logs`
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see this we're going to look inside the container using the `docker logs`
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-command. Let's use the container name Docker assigned.
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+command.
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+
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+Let's use the container name `insane_babbage`.
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$ docker logs insane_babbage
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$ docker logs insane_babbage
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hello world
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hello world
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@@ -172,29 +156,27 @@ command. Let's use the container name Docker assigned.
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hello world
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hello world
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. . .
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. . .
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-The `docker logs` command looks inside the container and returns its standard
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-output: in this case the output of our command `hello world`.
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+In this example:
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+
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+* `docker logs` looks inside the container and returns `hello world`.
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-Awesome! Our daemon is working and we've just created our first
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+Awesome! The daemon is working and you have just created your first
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Dockerized application!
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Dockerized application!
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-Now we've established we can create our own containers let's tidy up
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-after ourselves and stop our detached container. To do this we use the
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-`docker stop` command.
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+Next, run the `docker stop` command to stop our detached container.
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$ docker stop insane_babbage
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$ docker stop insane_babbage
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insane_babbage
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insane_babbage
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The `docker stop` command tells Docker to politely stop the running
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The `docker stop` command tells Docker to politely stop the running
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-container. If it succeeds it will return the name of the container it
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-has just stopped.
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+container and returns the name of the container it stopped.
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Let's check it worked with the `docker ps` command.
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Let's check it worked with the `docker ps` command.
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$ docker ps
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$ docker ps
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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-Excellent. Our container has been stopped.
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+Excellent. Our container is stopped.
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# Next steps
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# Next steps
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