Feature/getting started improvements

pages/docs/overview/start.md

@@ -9,19 +9,55 @@ toc: false
 ## Installation Quick Start
 
 ```bash
-git clone {{ site.repo }}.git
-cd singularity
-./autogen.sh
-./configure --prefix=/usr/local
-make
-sudo make install
+$ git clone {{ site.repo }}.git
+$ cd singularity
+$ ./autogen.sh
+$ ./configure --prefix=/usr/local
+$ make
+$ sudo make install
 ```
 
 ## Command Quick Start
 
+### Import a Centos7 image from Docker Hub
+
+The quickest way to get an image is to import it from Docker Hub.
+Here's an example that creates an empty image, imports the current
+CentOS 7 Docker image and proves that we got what we wanted.
+
+```terminal
+$ singularity create /tmp/Centos7.img
+Creating a new image with a maximum size of 768MiB...
+Executing image create helper
+Formatting image with ext3 file system
+Done.
+$ singularity import /tmp/Centos7.img docker://centos:7
+Cache folder set to /root/.singularity/docker
+Extracting /root/.singularity/docker/sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4.tar.gz
+Extracting /root/.singularity/docker/sha256:45a2e645736c4c66ef34acce2407ded21f7a9b231199d3b92d6c9776df264729.tar.gz
+Bootstrap initialization
+No bootstrap definition passed, updating container
+Executing Prebootstrap module
+Executing Postbootstrap module
+Done.
+$ singularity shell --contain /tmp/Centos7.img
+Singularity: Invoking an interactive shell within container...
+
+Singularity.Centos7.img> cat /etc/redhat-release
+CentOS Linux release 7.3.1611 (Core)
+Singularity.Centos7.img> exit
+exit
+$
+```
+
+This approach works with Docker's basic Alpine Linux
+(`docker://alpine`), Debian (`docker://debian`), Ubuntu
+(`docker://ubuntu`) and more.  You'll find the details on
+the [Singularity and Docker][docs-docker] page.
+
 ### Shell into container
 ```bash
-singularity shell --contain /tmp/Centos7.img 
+$ singularity shell --contain /tmp/Centos7.img 
 Singularity.Centos7.img> ps aux
 USER        PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
 gmk           1  0.0  0.3 115372  1768 pts/6    S    12:23   0:00 /bin/bash --norc --noprofile
@@ -32,35 +68,38 @@ Singularity.Centos7.img> exit
 ### I am the same user inside the container as outside the container
 
 ```bash
-id
+$ id
 uid=1000(gmk) gid=1000(gmk) groups=1000(gmk),10(wheel),2222(testgroup)
-singularity exec /tmp/Centos7.img id
+$ singularity exec /tmp/Centos7.img id
 uid=1000(gmk) gid=1000(gmk) groups=1000(gmk),10(wheel),2222(testgroup)
 ````
 
 ### Files on the host can be reachable from within the container
 ```bash
-echo "Hello World" > /home/gmk/testfile
-singularity exec /tmp/Centos7.img cat /home/gmk/testfile 
+$ echo "Hello World" > /home/gmk/testfile
+$ singularity exec /tmp/Centos7.img cat /home/gmk/testfile 
 Hello World
 ````
 
 ### Switching operating systems is as easy as pointing to a different image!
 ```bash
-singularity exec /tmp/Centos7.img cat /etc/redhat-release 
+$ singularity exec /tmp/Centos7.img cat /etc/redhat-release 
 CentOS Linux release 7.2.1511 (Core) 
 
-singularity exec /tmp/SL6.img cat /etc/redhat-release 
+$ singularity exec /tmp/SL6.img cat /etc/redhat-release 
 Scientific Linux release 6.8 (Carbon)
 
-singularity exec /tmp/Debian-stable.img cat /etc/debian_version
+$ singularity exec /tmp/Debian-stable.img cat /etc/debian_version
 8.5
 
-singularity exec /tmp/Ubuntu-trusty.img cat /etc/lsb-release 
+$ singularity exec /tmp/Ubuntu-trusty.img cat /etc/lsb-release 
 DISTRIB_ID=Ubuntu
 DISTRIB_RELEASE=14.04
 DISTRIB_CODENAME=trusty
 DISTRIB_DESCRIPTION="Ubuntu 14.04 LTS"
 ````
 
 {% include links.html %}
+
+[docs-docker]: /docs-docker
+[readme-bootstrapping]: https://github.com/singularityware/singularity/blob/master/README.md#bootstrapping-new-images