Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Overview of this book

The shell remains one of the most powerful tools on a computer system — yet a large number of users are unaware of how much one can accomplish with it. Using a combination of simple commands, we will see how to solve complex problems in day to day computer usage.Linux Shell Scripting Cookbook, Second Edition will take you through useful real-world recipes designed to make your daily life easy when working with the shell. The book shows the reader how to effectively use the shell to accomplish complex tasks with ease.The book discusses basics of using the shell, general commands and proceeds to show the reader how to use them to perform complex tasks with ease.Starting with the basics of the shell, we will learn simple commands with their usages allowing us to perform operations on files of different kind. The book then proceeds to explain text processing, web interaction and concludes with backups, monitoring and other sysadmin tasks.Linux Shell Scripting Cookbook, Second Edition serves as an excellent guide to solving day to day problems using the shell and few powerful commands together to create solutions.
Table of Contents (16 chapters)
Linux Shell Scripting Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Using loopback files


Loopback filesystems are very interesting components of Linux-like systems. We usually create filesystems on devices (for example, disk drive partitions). These storage devices are available as device files such as /dev/device_name. In order to use the storage device filesystem, we mount it at a directory called a mount point . On the other hand, loopback filesystems are those that we create in files rather than a physical device. We can then mount those files as filesystems at a mount point. This essentially lets you create logical "disks" inside a file on your physical disk!

How to do it...

Let us see how to create an ext4 filesystem on a file of size 1 GB:

  1. The following command will create a file that is 1 GB in size:

    $ dd if=/dev/zero of=loobackfile.img bs=1G count=1
    1024+0 records in
    1024+0 records out
    1073741824 bytes (1.1 GB) copied, 37.3155 s, 28.8 MB/s
    

    You can see that the size of the created file exceeds 1 GB. This is because the hard disk is a block device and...