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)

CLI, passing the arguments to the command line

Geopts is a Bash built-in widely used to efficiently parse switches and arguments passed on the command line of a script. We already saw other ways to accomplish this task, but getops makes it quite easy to handle it, since it can automatically recognize the switches and argument passed to the script. Its syntax is as follows:

getops options variable

The first thing we pass to getops is a string of options, the classical -a -x -f of whatever you want, without any leading dash, such as getops axf or also getops ax:f. If you see an option followed by a colon, this means that the option is meant to have an argument such as follows:

./our_script.sh -x our_argument -a

In our example, -x has an argument while -a is a simple switch, or we can also call it flag that can just be there or not, but it does not require any arguments. The options...