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, and user input are shown as follows: "Nagios Core will only need whatever information the ping(8) tool would need for its own check_ping command."

A block of code is set as follows:

define service {
    use                  generic-service
    host_name            sparta.example.net
    service_description  HTTP
    check_command        check_http
}

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

define host {
    host_name              sparta.example.net
    alias                  sparta
    address                192.0.2.21
    max_check_attempts     3
    check_period           24x7
    check_command          check-host-alive
    contacts               nagiosadmin
    notification_interval  60
    notification_period    24x7
}

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

# cd /usr/local/nagios/etc/objects
# vi sparta.example.net.cfg

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: "If the server restarted successfully, the web interface should show a brand new host in the Hosts list, in the PENDING state as it waits to run a check that the host is alive."