Conventions

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: "In the output, 4d3 tells us that line number 4 is deleted in file2. Similarly, the change command will show us changes in the file as well."

A block of code is set as follows:

#!/bin/bash
# This is comment line
echo "Hello World"
ls
date

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

$ expr 4 * 10
expr: syntax error
With command expr, we cannot use * for multiplication. We need to use \* for multiplication.
$ expr "4 * 10"
4 * 10
$ expr 4 \* 10
40

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

$ sed '1,3d' datafile >  tempfile
$ awk -F: '/Marie/{print $1, $2}' people1.txt

New terms and important words are shown in bold.

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.