How do I use expr for calculations?

To use expr for calculations in the command line, follow these steps:

Basic Syntax:

expr <expression>

Key Points:

1. Spaces: Ensure there are spaces around operators (e.g., +, -, *, /).
2. Operators:
   • Addition: +
   • Subtraction: -
   • Multiplication: * (use \* to escape it)
   • Division: /
   • Modulus: %

Examples:

1. Addition:

   expr 5 + 3

   Output: 8

2. Subtraction:

   expr 10 - 4

   Output: 6

3. Multiplication:

   expr 6 \* 7

   Output: 42

4. Division:

   expr 20 / 4

   Output: 5

5. Modulus:

   expr 10 % 3

   Output: 1

Using Variables:

You can also use variables with expr:

a=5
b=3
expr $a + $b

Output: 8

Note:

expr is useful for simple calculations, but for more complex arithmetic, consider using bc or arithmetic expansion $((...)).

Feel free to explore more about these commands in LabEx labs!