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Linux Shell Scripting Essentials

Linux Shell Scripting Essentials

By : Sinny Kumari
4.5 (2)
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Linux Shell Scripting Essentials

Linux Shell Scripting Essentials

4.5 (2)
By: Sinny Kumari

Overview of this book

Shell scripting is a quick method to prototype complex applications or problems. Shell scripts are a collection of commands to automate tasks, usually those for which the user has a repeated need, when working on Linux-based systems. Using simple commands or a combination of them in a shell can solve complex problems easily. This book starts with the basics, including essential commands that can be executed on Linux systems to perform tasks within a few nanoseconds. You’ll learn to use outputs from commands and transform them to show the data you require. Discover how to write shell scripts easily, execute script files, debug, and handle errors. Next, you’ll explore environment variables in shell programming and learn how to customize them and add a new environment. Finally, the book walks you through processes and how these interact with your shell scripts, along with how to use scripts to automate tasks and how to embed other languages and execute them.
Table of Contents (10 chapters)
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9
Index

Knowing the default environment

Setting up a proper environment is very important for running a process. An environment consists of environment variables that may or may not have a default value set. The required environment is set by modifying the existing environment variables or creating new environment variables. Environment variables are exported variables that are available to the current process and also its child processes. In Chapter 1, The Beginning of the Scripting Journey, we learned about some of the builtin shell variables that can be used in our application as environment variables to set the environment.

Viewing a shell environment

To view the current environment in the shell, we can use the printenv or env commands. Environment variables may have no value, a single value, or a multiple value set. If multiple values exist, each value is separated by a colon (:).

printenv

We can use printenv to print the value associated with a given environment variable. The syntax is as follows...

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