Feature/getting started improvements

pages/docs/overview/start.md

@@ -9,19 +9,42 @@ 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
 
+### Create a Centos7 image from a CentOS host
+
+It's easiest to build an image on a "compatible" host.  Here's a quick
+recipe to build a CentOS 7 image on a CentOS host.  See
+the [bootstrapping section][readme-bootstrapping] of the README for
+the full story and the [tutorials] for deeper advice.
+
+1. Create a file named `centos.def` that contains the following lines.
+
+   ```
+   BootStrap: yum
+   OSVersion: 7
+   MirrorURL: http://mirror.centos.org/centos-%{OSVERSION}/%{OSVERSION}/os/$basearch/
+   Include: yum
+   ```
+
+2. Create and bootstrap the image:
+
+   ```bash
+   $ sudo singularity create /tmp/Centos7.img
+   $ sudo singularity bootstrap /tmp/Centos7.img centos.def
+   ```
+
 ### 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 +55,37 @@ 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 %}
+
+[readme-bootstrapping]: https://github.com/singularityware/singularity/blob/master/README.md#bootstrapping-new-images