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: "The error_page directive installs a handler for an HTTP error based on the famous HTTP status codes."

A block of code is set as follows:

...
simple_command 4 "two";
# another_simple_command 0;

special_context {
    some_special_command /new/path;
    multiline_directive param {
        1 2 3 5 8 13;
    }
    include common_parameters;
}
...

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

Cache-Control:"max-age=1800"
Content-Encoding:"gzip"
Content-Type:"text/html; charset=UTF-8"
Date:"Sun, 10 Oct 2015 13:42:34 GMT"
Expires:"Sun, 10 Oct 2015 14:12:34 GMT"
Server:"nginx"
X-Cache:"EXPIRED"

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

% sudo nginx -t
nginx: [emerg] unexpected end of file, expecting "}" in /etc/nginx/nginx.conf:1
nginx: configuration file /etc/nginx/nginx.conf test failed

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 should have a way to reboot an otherwise unreachable server; every sane modern hosting provider has it, whether in the form of a simple menu item Reboot, such as in Amazon EC2 or a whole IPMI console access."