In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "It can be turned on by doing shell access to BeagleBone and executing command sudo ifconfig usb0 up."

A block of code is set as follows:

var b = require('bonescript'),
var state = b.HIGH;

b.pinMode("USR3", b.OUTPUT);
b.digitalWrite("USR3", state);

setInterval(blink,1000);

function blink()
{
  if(state == b.LOW)
    state = b.HIGH;
  else
    state = b.LOW;
  b.digitalWrite("USR3", state);
}

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

sudo dd  if=<image_file_path> of=/dev/sdx bs=1M ; sync

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "You can stop the loop by clicking on the red Stop button in Cloud9."