polishing things up a bit

Author: GodloveD

01-basic-usage/README.md

@@ -12,7 +12,7 @@ In this class, we'll be using containers from:
 There are lots of other places to find pre-build containers too. Here are some of the more popular ones:
 
 - [Singularity Hub](https://singularity-hub.org/), an early collaboration between Stanford University and the Singularity community
-- [Quay.io](quay.io), developed and maintained by Red Hat
+- [Quay.io](https://quay.io/), developed and maintained by Red Hat
 - [NGC](https://ngc.nvidia.com/catalog/all?orderBy=modifiedDESC&pageNumber=3&query=&quickFilter=&filters=), developed and maintained by NVIDIA
 - [BioContainers](https://biocontainers.pro/#/registry), develped and maintained by the Bioconda group
 - Cloud providers like Amazon AWS, Microsoft Azure, and Google cloud also have container registries that can work with Singularity
@@ -22,6 +22,8 @@ There are lots of other places to find pre-build containers too. Here are some o
 In the last section, we validated our Singularity installation by "running" a container from the Container Library. Let's download that container using the `pull` command.
 
 ```
+$ cd ~
+
 $ singularity pull library://godlovedc/funny/lolcow
 ```
 

02-building/README.md

@@ -71,7 +71,7 @@ Depending on the environment on your host system you may see your prompt change.
 Let's try installing some software. I used the programs `fortune`, `cowsay`, and `lolcat` to produce the container that we saw in the first demo.
 
 ```
-Singularity> Singularity> sudo apt-get update && apt-get -y install fortune cowsay lolcat
+Singularity> sudo apt-get update
 bash: sudo: command not found
 ```
 
@@ -102,7 +102,9 @@ Now we are the root user inside the container. Note also the addition of the `--
 Let's try installing our software again.
 
 ```
-Singularity> apt-get update && apt-get -y install fortune cowsay lolcat
+Singularity> apt-get update
+
+Singularity> apt-get install -y fortune cowsay lolcat
 ```
 
 Now you should see the programs successfully installed.  Let's try running the demo in this new container.
@@ -147,10 +149,10 @@ If  you receive warnings from the Perl language about the `locale` being incorre
 
 We changed our path in this session, but those changes will disappear as soon as we exit the container just like they will when you exit any other shell.  To make the changes permanent we should add them to the definition file and re-bootstrap the container.  We'll do that in a minute.
 
-## Building the final production-grade SIF file
-
 ---
 
+## Building the final production-grade SIF file
+
 Although it is fine to shell into your Singularity container and make changes while you are debugging, you ultimately want all of these changes to be reflected in your definition file.  Otherwise if you need to reproduce it from scratch you will forget all of the changes you made. You will also want to rebuild you container into something more durable, portable, and robust than a directory.  
 
 Let's update our definition file with the changes we made to this container.

03-the-ecosystem/README.md

@@ -6,7 +6,7 @@ We've spent a lot of time on building and using your own containers so that you
 
 ## Tags and hashes
 
-First, Docker Hub and the container library both have a concept of a tagged image. Tags make it convenient for developers to release several different versions of the same container. For instance, if you wanted to specify that you need Debian version 9, you could do so like this:
+First, Docker Hub and the Container Library both have a concept of a tagged image. Tags make it convenient for developers to release several different versions of the same container. For instance, if you wanted to specify that you need Debian version 9, you could do so like this:
 
 ```
 $ singularity pull library://debian:9
@@ -25,7 +25,13 @@ There is a _special_ tag in both the Singularity Library and Docker Hub called *
 Tags are not immutable and may change without warning. For insance, the latest tag is automatically assigned to the latest build of a container in Docker Hub. So pulling by tag (or pulling `latest` by default) can result in your pulling 2 different images with the same command. If you are interested in pulling the same container multiple times, you should pull by the hash. Continuing with our Debian 9 example, this will ensure that you get the same one even if the developers change that tag:
 
 ```
-$ singularity pull debian:sha256.b92c7fdfcc6152b983deb9fde5a2d1083183998c11fb3ff3b89c0efc7b240448
+$ singularity pull library://debian:sha256.b92c7fdfcc6152b983deb9fde5a2d1083183998c11fb3ff3b89c0efc7b240448
+```
+
+The syntax to do the same from Docker Hub is a bit different:
+
+```
+$ singularity pull docker://debian@sha256:f17410575376cc2ad0f6f172699ee825a51588f54f6d72bbfeef6e2fa9a57e2f
 ```
 
 ## Default entities and collections

06-fake-installation/README.md

@@ -11,7 +11,7 @@ First, we will `cd` back into our `~/lolcow` directory (if we are not already th
 ---
 **NOTE**
 
-This class is taught using virtual machines, but you should still _always_ be careful and double check your location, permissions, and mental state before issuing a `rm -rf` command. That goes double when issuing the command as root.
+This class is taught using virtual machines, but you should still _always_ be careful and double check your location, permissions, and mental state before issuing a `rm -rf` command. That goes _double_ when issuing the command as root.
 
 ---
 

README.md

@@ -77,7 +77,7 @@ Docker shines for DevOPs teams providing cloud-native micro-services to users.
 
 ## Singularity
 
-[Singularity](http://singularity.lbl.gov/) is a relatively new container software originally developed by Greg Kurtzer while at Lawrence Berkley National labs.  It was developed with security, scientific software, and HPC systems in mind.  
+[Singularity](http://singularity.lbl.gov/) is a relatively new container software invented by Greg Kurtzer while at Lawrence Berkley National labs and now developed by his company [Sylabs](sylabs.io).  It was developed with security, scientific software, and HPC systems in mind.  
 
 **philosophy**