Book Image

Bash Cookbook

By : Ron Brash, Ganesh Sanjiv Naik
Book Image

Bash Cookbook

By: Ron Brash, Ganesh Sanjiv Naik

Overview of this book

In Linux, one of the most commonly used and most powerful tools is the Bash shell. With its collection of engaging recipes, Bash Cookbook takes you through a series of exercises designed to teach you how to effectively use the Bash shell in order to create and execute your own scripts. The book starts by introducing you to the basics of using the Bash shell, also teaching you the fundamentals of generating any input from a command. With the help of a number of exercises, you will get to grips with the automation of daily tasks for sysadmins and power users. Once you have a hands-on understanding of the subject, you will move on to exploring more advanced projects that can solve real-world problems comprehensively on a Linux system. In addition to this, you will discover projects such as creating an application with a menu, beginning scripts on startup, parsing and displaying human-readable information, and executing remote commands with authentication using self-generated Secure Shell (SSH) keys. By the end of this book, you will have gained significant experience of solving real-world problems, from automating routine tasks to managing your systems and creating your own scripts.
Table of Contents (15 chapters)
Title Page
Copyright and Credits
Packt Upsell
Contributors
Preface
Index

Compiling and installing your own Bash shell


In this recipe, we are going to learn about compile and install the Bash shell. We are going to use SHC, which is shell script compiler.

 

Getting ready

Besides having a terminal open, make sure you have SHC installed in your system.

How to do it...

Now we will write a simple shell script that will print “Hello World”. Using SHC, the Shell script will be converted into binaries directly. Create a script hello.sh, and write the following content in it.

#!/bin/bash
echo "Hello World"
a=10
b=20
c=$((a+b))
echo $c

Now, to log all commands, run the logger command as follows:

$ logger -f hello.sh

How it works...

After executing the script, two extra files will be created. The files are:

  • hello.sh.x: This file is the stripped binary encrypted shell script in binary format
  • hello.sh.x.c: This file is the C source code of hello.sh

Now, execute the encrypted shell script as follows:

$ ./hello.sh.x

The logger command will make an entry about your file in the syslog file...