Arithmetic Expressions
The let command performs arithmetic. Bash is restricted to integer arithmetic. The shell provides a way to substitute arithmetic values (for use as command arguments or in variables); base conversion is also possible:
| Use the value of the enclosed arithmetic expression. |
| Interpret integer
n in numeric base B. For
example, |
Operators
The shell uses arithmetic operators from the C programming language, in decreasing order of precedence.
Operator | Description |
| Auto-increment and auto-decrement, both prefix and postfix |
| Unary plus and minus |
| Logical negation and binary inversion (one’s complement) |
| Exponentiation[a] |
| Multiplication, division, modulus (remainder) |
| Addition, subtraction |
| Bitwise left shift, bitwise right shift |
| Less than, less than or equal to, greater than, greater than or equal to |
| Equality, inequality (both evaluated left to right) |
| Bitwise AND |
| Bitwise exclusive OR |
| Bitwise OR |
| Logical AND (short circuit) |
| Logical OR (short circuit) |
| Inline conditional evaluation |
| |
| |
| Assignment |
| |
| Sequential expression evaluation |
[a] The | |
Examples
let "count=0" "i = i + 1" Assign values to i and count let "num % 2" Exit successfully if num is even (( percent >= 0 && \ percent <= 100 )) Test the range of a value ...