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
About the Authors
About the Reviewers

Cryptographic tools and hashes

Encryption techniques are used mainly to protect data from unauthorized access. There are many algorithms available and we have discussed the most commonly used ones. There are a few tools available in a Linux environment for performing encryption and decryption. Sometimes we use encryption algorithm hashes for verifying data integrity. This section will introduce a few commonly used cryptographic tools and a general set of algorithms that these tools can handle.

How to do it...

Let us see how to use tools such as crypt, gpg, base64, md5sum, sha1sum, and openssl:

  • The crypt command is a simple and relatively insecure cryptographic utility that takes a file from stdin and a passphrase as input and output encrypted data into stdout (and, hence, we use redirection for the input and output files):

    $ crypt <input_file >output_file
    Enter passphrase:

    It will interactively ask for a passphrase. We can also provide a passphrase through command-line arguments:

    $ crypt...