Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "This file, temperatures.csv, is available as a download and once downloaded, you can move it into hdfs by running the command, as shown in the following code."

A block of code is set as follows:

hdfs dfs -copyFromLocal temperatures.csv /user/normal

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

Map-Reduce Framework -- output average temperature per city name
    Map input records=35
    Map output records=33
    Map output bytes=208
    Map output materialized bytes=286

Any command-line input or output is written as follows:

$ ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa
$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
$ chmod 0600 ~/.ssh/authorized_keys

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Clicking on the Datanodes tab shows all the nodes."

Warnings or important notes appear like this.

Tips and tricks appear like this.