Demonstrate how to declare and use variables in a shell script.

In shell scripting, variables are used to store and manipulate data. They allow you to store values and refer to them by a name throughout your script. Let's explore how to declare and use variables in a shell script, specifically using the Bash shell. 1. Variable Declaration: * To declare a variable, you simply assign a value to it using the assignment operator (`=`). No spaces are allowed around the equals sign. * Variable names in shell scripting are case-sensitive and can consist of letters, digits, and underscores. However, they should start with a letter or an underscore. * Here's an example of declaring variables in a shell script: ``` bash`#!/bin/bash # Declare a variable with a string value name="John Doe" # Declare a variable with a numeric value age=30 # Declare a variable with a command substitution c....