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Bash Scripting for Beginners: Complete Guide to Getting Started - Basic Math (Part 4)

2 min read 12 days ago
Published on Sep 16, 2024 This response is partially generated with the help of AI. It may contain inaccuracies.

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Introduction

This tutorial is designed for beginners looking to understand how to perform basic math operations in Bash scripting. Unlike other programming languages, Bash handles mathematical expressions differently, which can lead to confusion. This guide will clarify these differences and provide step-by-step instructions on using Bash for simple math tasks.

Step 1: Understand Bash Math Operations

  • Bash does not support direct arithmetic operations using standard operators like +, -, *, and / without specific commands.
  • To perform calculations, you can use:
    • The expr command
    • The built-in arithmetic expansion $(( ))

Step 2: Using the Evaluate Expression Command

  • The expr command allows you to evaluate expressions in Bash.
  • Here’s how to use it:
    1. Open your terminal.
    2. Type the following command to add two numbers:
      expr 5 + 3
    3. To subtract, use:
      expr 10 - 4
    4. For multiplication, remember to escape the asterisk *:
      expr 6 \* 7
    5. For division:
      expr 20 / 4

Step 3: Multiplication in Bash

  • When performing multiplication, use the escape character \ before the asterisk to prevent the shell from interpreting it as a wildcard.
  • Example of multiplication:
    result=$(expr 6 \* 7)
echo $result  # Outputs 42

Step 4: Using Variables with Math Expressions

  • You can store values in variables and use them in math operations.
  • Example:
    1. Define variables:
      a=5
b=3
    2. Perform addition:
      sum=$(expr $a + $b)
echo $sum  # Outputs 8
    3. For multiplication:
      product=$(expr $a \* $b)
echo $product  # Outputs 15

Conclusion

In this tutorial, you learned how to perform basic math operations in Bash using the expr command and variable assignments. Remember to use the escape character for multiplication and explore using variables to make your scripts more dynamic. As you progress, consider experimenting with more complex mathematical expressions and integrating them into your Bash scripts for automation tasks. Happy scripting!

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