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Hadoop Beginner's Guide

You're reading from   Hadoop Beginner's Guide Get your mountain of data under control with Hadoop. This guide requires no prior knowledge of the software or cloud services ‚Äì just a willingness to learn the basics from this practical step-by-step tutorial.

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Product type Paperback
Published in Feb 2013
Publisher Packt
ISBN-13 9781849517300
Length 398 pages
Edition 1st Edition
Tools
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Toc

Table of Contents (19) Chapters Close

Hadoop Beginner's Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
1. What It's All About 2. Getting Hadoop Up and Running FREE CHAPTER 3. Understanding MapReduce 4. Developing MapReduce Programs 5. Advanced MapReduce Techniques 6. When Things Break 7. Keeping Things Running 8. A Relational View on Data with Hive 9. Working with Relational Databases 10. Data Collection with Flume 11. Where to Go Next Pop Quiz Answers Index

Time for action – demonstrating the default security


When we have previously shown listings of files, we have seen user and group names for them. However, we have not really explored what that means. Let's do so.

  1. Create a test text file in the Hadoop user's home directory.

    $ echo "I can read this!" >  security-test.txt 
    $ hadoop fs -put security-test.txt  security-test.txt 
    
  2. Change the permissions on the file to be accessible only by the owner.

    $ hadoop fs -chmod 700 security-test.txt 
    $ hadoop fs -ls
    

    The output of the preceding command can be shown in the following screenshot:

  3. Confirm you can still read the file.

    $ hadoop fs -cat security-test.txt 
    

    You'll see the following line on the screen:

    I can read this!
    
  4. Connect to another node in the cluster and try to read the file from there.

    $ ssh node2
    $ hadoop fs -cat security-test.txt 
    

    You'll see the following line on the screen:

    I can read this!
    
  5. Log out from the other node.

    $ exit
    
  6. Create a home directory for another user and give them ownership...

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