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Introduction to the Linux Command Line on Raspberry Pi OS

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Getting Started with the Command Line
Managing Files and Directories
Managing Software
System Monitoring and Management
Networking Basics
Scripting Basics
Working with Git (Optional Advanced Topic)
Final Project: Building a Simple Command Line Application
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Basic Scripting Constructs

Learn how to use conditional statements, loops, and variables in your shell scripts.

By Kevin McAleer,    2 Minutes

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Introduction

Shell scripts become more powerful when you use programming constructs like conditional statements, loops, and variables. In this lesson, you’ll learn how to use these basic scripting constructs to make your scripts more dynamic and functional.

Learning Objectives

  • Use variables in shell scripts.
  • Implement conditional statements (if, else).
  • Use loops (for, while) to repeat tasks.

Using Variables in Shell Scripts

Variables allow you to store and reuse values in your scripts. To define a variable and use it:

    #!/bin/bash
    name="Raspberry Pi"
    echo "Hello, $name!"

Note that the variable name should not have spaces around the = sign. Also note when the variable is used, it is prefixed with a $; $name in this case.

Conditional Statements

Conditional statements enable your script to make decisions. Here’s a basic example using if and else:

    #!/bin/bash
    if [ -f "/etc/passwd" ]; then
        echo "The file exists."
    else
        echo "The file does not exist."
    fi

Using Loops

Loops allow you to repeat tasks multiple times. Here’s an example of a for loop:

    #!/bin/bash
    for i in 1 2 3 4 5
    do
        echo "Iteration $i"
    done

And a while loop:

    #!/bin/bash
    count=1
    while [ $count -le 5 ]
    do
        echo "Count is $count"
        count=$((count + 1))
    done

Summary

In this lesson, you learned how to use variables, conditional statements, and loops in your shell scripts. These constructs make your scripts more powerful and flexible, allowing you to automate complex tasks more effectively.

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