Book Image

Mastering Bash

By : Giorgio Zarrelli
Book Image

Mastering Bash

By: Giorgio Zarrelli

Overview of this book

System administration is an everyday effort that involves a lot of tedious tasks, and devious pits. Knowing your environment is the key to unleashing the most powerful solution that will make your life easy as an administrator, and show you the path to new heights. Bash is your Swiss army knife to set up your working or home environment as you want, when you want. This book will enable you to customize your system step by step, making your own real, virtual, home out of it. The journey will take you swiftly through the basis of the shell programming in Bash to more interesting and challenging tasks. You will be introduced to one of the most famous open source monitoring systems—Nagios, and write complex programs with it in any languages. You’ll see how to perform checks on your sites and applications. Moving on, you’ll discover how to write your own daemons so you can create your services and take advantage of inter-process communication to let your scripts talk to each other. So, despite these being everyday tasks, you’ll have a lot of fun on the way. By the end of the book, you will have gained advanced knowledge of Bash that will help you automate routine tasks and manage your systems.
Table of Contents (15 chapters)

Returning code and thresholds

Before coding a plugin, we must face some concepts that will be the stepping stone of our Nagios code base, one of these being the return codes of the plugin itself. As we already discussed, once the plugin collects the data about how the service is going, it evaluates these data and determines if the situation falls under one of the following status:

Return code

Status

Description

0

OK

The plugin checked the service and the results that are inside the acceptable range.

1

WARNING

The plugin checked the service and the results that are above a WARNING threshold. We must keep an eye on the service.

2

CRITICAL

The plugin checked the service and the results that are above a CRITICAL threshold or the service not responding. We must react now.

3

UNKNOWN

Either we passed the wrong arguments to the plugin or there is...