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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

Passing command line parameters to script

So far, we have seen the usage of the commands such as grep, head, ls, cat, and many more. These commands also support passing arguments to a command via a command line. Some of command line arguments are input files, output files, and options. Arguments are provided as per output needs. For example, ls -l filename is executed to get a long listing output, while ls -R filename is used to display recursively the contents of a directory.

Shell script also supports providing command line arguments that we can process further by a shell script.

The command line arguments can be given as follows:

<script_file> arg1 arg2 arg3 … argN

Here, script_file is a shell script file to be executed, and arg1, arg2, arg3, argN, and so on, are command line parameters.

Reading arguments in scripts

Command line arguments are passed to a shell script as positional parameters. So, arg1 will be accessed in a script as $1, arg2 as $2, and so on.

The following shell...

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