Building groups using regular expressions

In this recipe, we'll learn a shortcut for building groups of hosts using regular expressions tested against their hostnames.

This recipe is likely only of use to you if you use a naming convention for your hosts that allows them to be reasonably grouped by location, function, or some other useful metric by a common string in their hostnames.

Getting ready

You will need to have a server running Nagios Core 3.0 or later, have access to the command line to change its configuration, and understand the basics of how hostgroups and servicegroups work. These are covered in the Creating a new hostgroup and Creating a new servicegroup recipes in Chapter 1.

In this example, we'll group three existing hosts named web-server-01, web-server-02, and web-server-03 into a new hostgroup, web-servers, based only on their hostnames.

It would help to have some familiarity with regular expressions, but the recipe includes a simple example, which should meet many use cases...