more docker tutorial work

I'm not sure if I want to get into Dockerfiles. There's already a
lot here.

README

@@ -5,7 +5,7 @@ with it.
 
 What is docker? You can think of it like a lightweight VM. It's
 really considerably different, because it uses the host processor,
-memory, network stack, etc., without creating virutal hardware. We
+memory, network stack, etc., without creating virtual hardware. We
 can throw around terms like user-level filesystems, process groups,
 and network namespaces, but the important part is that you can run
 a self-contained guest Linux OS within another host Linux OS, with
@@ -14,8 +14,8 @@ the resources given to it by the host, so it provides some (minimal)
 level of security. It also means we can start a process from a
 known-clean state, so we have repeatability.
 
-Exercise 1: Docker Images
-=========================
+Docker Images
+=============
 
 Let's start with the concept of an *image*. This is the self-contained
 guest Linux OS, which is configured to automatically run some process
@@ -38,7 +38,7 @@ docker we only want one image, and it's the one with the *tag*
 
 When the command completes, try running
 
-    docker image list
+    docker images
 
 You should see something like:
 
@@ -54,7 +54,7 @@ We can do a few things with this image, aside from running it. Try
 the following:
 
     docker tag ubuntu:16.04 my_ubuntu
-    docker image list
+    docker images
 
 Note that we now see the same image ID twice, but with different
 names. By default, a repository (the tagless part of an image name)
@@ -62,7 +62,7 @@ is tagged as "latest" if you don't specify one. Let's try specifying
 a tag, though:
 
     docker tag ubuntu:16.04 foo:bar
-    docker image list
+    docker images
 
 The results should not be surprising.
 
@@ -71,7 +71,7 @@ it's good to know how to clean these up. Let's get rid of our new
 tagged images:
 
     docker rmi my_ubuntu:latest foo:bar
-    docker image list
+    docker images
 
 A common problem is that we'll end up reusing an old tag, leaving
 an image with no repository:tag name. These show up as "<none>:<none>".
@@ -83,7 +83,159 @@ For the curious, feel free to read the man pages for awk and xargs.
 This is not going to be essential information for this course,
 though.
 
+The commands here are largely from an older version of docker. Now they're
+aliases to new-style commands. Here's the mapping:
 
-Exercise 2: Running an Image in a Container
-===========================================
+|  Old Command  |    New Command    |
+| ------------- | ----------------- |
+| docker images | docker image list |
+| docker pull   | docker image pull |
+| docker rmi    | docker image rm   |
+| docker tag    | docker image tag  |
 
+
+Running an Image in a Container
+===============================
+
+Images are all fine and good, but we actually want to use docker to *do*
+something, which means we have to run these images. An image runs in a
+*container*. The container has system resources allocated to it, and runs
+a program or programs that exist in the image. A container runs a single
+image, but an image may be running in multiple containers.
+
+Containers can also be started with various options, such as elevated
+privileges, mounted volumes, environment variables, and so on. The most
+basic invocation is
+
+    docker run ubuntu:16.04
+
+If you run this, you'll find that it pauses for a second or so, and then
+returns to the command line. If you want to see running containers, run
+
+    docker ps
+
+You see headings, but probably no actual containers. Now, try
+
+    docker ps -a
+
+Now we have something! Here's an example of what you might see:
+
+    CONTAINER ID        IMAGE               COMMAND             CREATED              STATUS                          PORTS               NAMES
+    1b937126d5bc        ubuntu:16.04        "/bin/bash"         About a minute ago   Exited (0) About a minute ago                       upbeat_archimedes
+
+Let's parse this out:
+
+  - The container ID is a unique ID, like the image ID we saw before
+  - The image should be self-explanatory
+  - The command is what the container ran. In this case, it's just bash
+  - The created time is when the container was started
+  - The status tells us that this container exited, and is no longer running
+  - We have no ports bound, but if we did these would map from local
+    network ports to network ports on the container
+  - The names are symbolic names used to refer to this container, and are
+    synonyms for the container ID
+
+By default, names are assigned randomly according to the pattern
+<adjective>_<scientist>
+
+We can assign a name to the container, which is often useful:
+
+    docker run --name=bash_test ubuntu:16.04
+
+This will behave similarly to the previous command, but if we run
+
+    docker ps -a
+
+We'll now see our container named "bash_test" along with whatever random name
+our first container was assigned.
+
+Usually, an image is defined to do something useful when run non-interactively.
+We can get interactive access to the container, though, as follows:
+
+    docker run -ti ubuntu:16.04
+
+We've passed two new options to docker run. The "-t" option allocates a
+pseudo-TTY, and the "-i" option makes the container interactive. You should
+now have a shell on the container running as root! If you run "docker ps" in
+another terminal, you will see that the container status is
+"Up <length of time>"
+
+When you're done playing around in this shell, exit to stop the container.
+
+At this point, you probably want to get rid of these stopped containers. Run:
+
+    docker rm bash_test
+    docker ps -a
+    
+You'll still have the two randomly-named containers, but the one named
+"bash_test" should no longer be present. Remove the other two, as well.
+
+We don't have to run the configured program in a container; we can run any
+command that's present on the image. Let's see this in action:
+
+    docker run ubuntu:16.04 /bin/date
+
+That should print the date in the container. It's probably in UTC, while running
+/bin/date on your VM should print the date in Eastern US time (EST or EDT). You
+can also specify options:
+
+    docker run ubuntu:16.04 ls /var
+
+Another very useful option is "--rm", which will get rid of the container once
+it stops:
+
+    docker run --rm --name="rm_test" ubuntu:16.04 ls /var
+
+We've once again been using old-style commands, which are aliases:
+
+| Old Command |     New Command      |
+| ----------- | -------------------- |
+| docker run  | docker container run |
+| docker ps   | docker container ls  |
+
+
+Stopping a Running Container
+============================
+
+A container might become unresponsive, or it might be a long-running service
+that you want to terminate. You can do this with either of the following:
+
+    docker kill <container>
+    docker stop <container>
+
+"stop" is more graceful, trying SIGTERM first, and then SIGKILL. "kill" sends
+SIGKILL by default, but this can be overridden on the command line.
+
+| Old Command |      New Command      |
+| ----------- | --------------------- |
+| docker kill | docker container kill |
+| docker stop | docker container stop |
+
+
+Removing Stopped Containers
+===========================
+
+As with images, you'll tend to accumulate lots of stopped containers, unless
+you've run them all with the "--rm" option. Fortunately, we can get rid of
+these with
+
+    docker rm <container>
+
+which is now an alias for
+
+    docker container rm <container>
+
+
+Other Options for Running Containers
+====================================
+
+Here are some useful options you might want to use:
+
+| Option |    Argument     |                  Effect                   |
+| ------ | --------------- | ----------------------------------------- |
+| --rm   |                 | removes container after exit              |
+| -ti    |                 | run interactively with a pTTY             |
+| -e     |     <vars>      | set environment variables                 |
+| -h     |   <hostname>    | set the container's hostname              |
+| -p     | <hport>:<cport> | map host's <hport> to container's <cport> |
+| -v     |  <hdir>:<cdir>  | mount host's <hdir> on <cdir>             |