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The Shell
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2014-07-30

Introduction to cloud computing

Learning Objectives

  • Understand benefits of working on a remote computer system
  • Be able to connect to a cloud instance
  • Introducing the Shell and understanding how to use it
  • Check the available resources and file system on your remote machine

There are a number of reasons why accessing a remote machine is invaluable to any scientists working with large datasets. In the early history of computing, working on a remote machine was standard practice - computers were bulky and expensive. Today we work on laptops that are more powerful than the sum of the world's computing capacity 20 years ago, but many analyses (especially in genomics) won't work on these laptops and must be run on remote machines.

You'll know you need to start working on the cloud when...

  • Your computer does not have enough resources to run the desired analysis (memory, processors, disk space, network bandwidth).
  • Your computer is taking hours or days to get through an analysis.
  • You cannot install software on your computer (application does not have support for your operating system, conflicts with other existing applications, etc.)

The cloud is a part of our everyday life (e.g. using Amazon, Google, Netflix, or an ATM involves remote computing). The topic is fascinating but this lesson says '5 minutes or less' so let's get connected.

Setting up

For the duration of this workshop, we will be accessing data and tools required to analyze our data on a remote computer using the Amazon's Elastic Compute Cloud (EC2).

Connecting to a remote computer using Amazon EC2

This is the first and last place in these lessons where it will matter if you are using PC, Mac, or Linux. After we connect, we will all be on the same operating system/computing environment.

To save time, your instructor will have launched an remote computer (instance) for you prior to the workshop. Each instance will have an associated IP adresss listed in the etherpad which you will need to connect to the instance. If you are following these lessons on your own, or after the workshop see the lesson on cloud computing for instructions on how to do this yourself.

User Credentials

To logon to the remote computer you will require the following credentials (NOTE: they are case sensitive):

  • Username: dcuser
  • Password: data4Carp

The Shell

The shell is a program that presents a command line interface which allows you to control your computer using commands entered with a keyboard instead of controlling graphical user interfaces (GUIs) with a mouse/keyboard combination. The shell is an interpreter that helps translate our input into computer language.

There are many reasons to learn about the shell.

  • For most bioinformatics tools, you have to use the shell. There is no graphical interface. If you want to work in metagenomics or genomics you're going to need to use the shell.
  • The shell gives you power. The command line gives you the power to do your work more efficiently and more quickly. When you need to do things tens to hundreds of times, knowing how to use the shell is transformative.
  • Computational resources that can handle large datasets, such as remote computers or cloud computing, require a working knowledge of Unix.

We will be using the shell on our laptops to connect to the cloud. How do we access the shell?

Mac users

The shell is already available on Mac and Linux computers.

On Mac the shell is available through Terminal Applications -> Utilities -> Terminal

Simply search for 'Terminal' and/or look for the terminal icon.
terminal icon

  1. Open the terminal and type the following command substituting 'ip_address' for the IP address your instructor will provide. Be sure to pay attention to capitalization and spaces

    $ ssh dcuser@ip_address
    
  2. You will receive a security message that looks something like the message below. Type 'yes' to proceed.

    The authenticity of host 'ec2-52-91-14-206.compute-1.amazonaws.com (52.91.14.206)' can't be established. ECDSA key fingerprint is SHA256:S2mMV8mCThjJHm0sUmK2iOE5DBqs8HiJr6pL3x/XxkI. Are you sure you want to continue connecting (yes/no)?
    
  3. In the final step, you will be asked to provide a login and password. Note: When typing your password, it is common in Unix/Linux not see see any asterisks (e.g. ****) or moving cursors. Just continue typing.

  4. You should now be connected!

Windows users

Prerequisites: You must have an SSH client. There are several free options and we will use PuTTY [Download Putty.exe]

For Windows, you will have downloaded a separate program called PuTTy to allow you to use the shell.

  1. Open PuTTY; In the 'Host Name (or IP address)' section paste in the IP address provided by your instructor (or the ip address of an instance you have provisioned yourself). Keep the default selection 'SSH' and Port (22).
    Putty Image
  2. Click 'Open' and you will be presented with a security warning. Select 'Yes' to continue to connect.
    Putty security screen
  3. In the final step, you will be asked to provide a login and password. Note: When typing your password, it is common in Unix/Linux not see see any asterisks (e.g. ****) or moving cursors. Just continue typing.
    Putty login
  4. You should now be connected!

Verifying your connection and environment

When you connect, it is typical to receive a welcome screen. The Data Carpentry Amazon instances display this message upon connecting:

Welcome to Ubuntu 14.04.3 LTS (GNU/Linux 3.13.0-48-generic x86_64)

 * Documentation:  https://help.ubuntu.com/

  System information as of Sun Jan 24 21:38:35 UTC 2016

  System load:  0.0                Processes:           151
  Usage of /:   48.4% of 98.30GB   Users logged in:     0
  Memory usage: 6%                 IP address for eth0: 172.31.62.209
  Swap usage:   0%

  Graph this data and manage this system at:
    https://landscape.canonical.com/

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

12 packages can be updated.
10 updates are security updates.


Last login: Sun Jan 24 21:38:36 2016 from

You should also have a blinking cursor awaiting your command

dcuser@ip-172-31-62-209 ~ $

Resources on cloud computing

Learn more about cloud computing in bioinformatics Fusaro VA, Patil P, Gafni E, Wall DP, Tonellato PJ (2011) Biomedical Cloud Computing With Amazon Web Services. PLoS Comput Biol 7(8): e1002147. doi: 10.1371/journal.pcbi.1002147

Resources on the shell