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| Chapter 4 The Bourne Shell and Korn Shell |

## 4.4 Arithmetic Expressions

The Korn shell's let command performs integer arithmetic. The Korn shell provides a way to substitute integer values (for use as command arguments or in variables); base conversion is also possible:

$(( `expr` )) | Use the value of the enclosed arithmetic expression.
`B`#`n` | Interpret integer `n` in numeric base `B`. For example, 8#100 specifies the octal equivalent of decimal 64.

### 4.4.1 Operators

The Korn shell uses arithmetic operators from the C programming language; they are listed below in decreasing order of precedence:

- | Unary minus.
! ~ | Logical negation; binary inversion (one's complement).
* / % | Multiplication; division; modulus (remainder).
+ - | Addition; subtraction.
<< >> | Bitwise left shift; bitwise right shift.
<= >= | Less than or equal to; greater than or equal to.
< > | Less than; greater than.
== != | Equality; inequality (both evaluated left to right).
& | Bitwise AND.
^ | Bitwise exclusive OR.
| | Bitwise OR.
&& | Logical AND.
|| | Logical OR.
*= /= %= | Assignment.
= += -= |
<<= >>= |
&= ^= |= |

### 4.4.2 Examples

See the let command for more information and examples.

>     let "count=0" "i = i + 1"	Assign i and count.
>     let "num % 2"	Test for an even number.
>     (( percent >= 0 && percent <= 100 ))	Test the range of a value.

4.3 Variables |  | 4.5 Command History