Bash Math Functions

Introduction to Math Functions in Bash

• Bash offers a variety of built-in commands and functions.
• This video focuses on math functions in Bash.

Handling Math in Bash

• Math functions are not frequently used but contribute to a well-rounded knowledge of Bash.
• Different shells and programming languages handle math differently.
• Example: In Python, adding 30 and 10 can be done directly as 30 + 10.

Evaluating Expressions with expr

• Bash requires a specific syntax to understand math operations.
• The expr command is used to evaluate expressions.
• Example: expr 30 + 10 will output 40.

Basic Arithmetic Operations

• Addition: Use expr followed by the numbers with a plus symbol.
  • Example: expr 30 + 10
• Subtraction: Use expr followed by the numbers with a minus symbol.
  • Example: expr 30 - 10 outputs 20.
• Division: Use expr followed by the numbers with a forward slash.
  • Example: expr 30 / 10 outputs 3.

Multiplication and Escaping Special Characters

• Multiplication: Use expr with an escaped asterisk.
• The asterisk * is a wildcard in Bash, meaning "everything".
• To use it for multiplication, escape it with a backslash \.
  • Example: expr 100 \* 4
• Escaping special characters is necessary when they have other purposes in Bash.

Using Variables in Math Functions

• Variables can be used in math functions.
• Example:
  • my_num1=100
  • expr $my_num1 + 50 will output 150.
• Another Example:
  • my_num2=200
  • expr $my_num1 + $my_num2 will output 300.

Practical Application and Conclusion

• This knowledge may not seem immediately useful but can be helpful in future scenarios.
• It provides a foundation for performing math functions in Bash, especially for those familiar with other shells or programming languages.