[Chapter 4] 4.4 Arithmetic Expressions

4.4 Arithmetic Expressions

The Korn shell's let command performs arithmetic. ksh88 is restricted to integer arithmetic. ksh93 can do floating-point arithmetic as well. The Korn shell provides a way to substitute arithmetic 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; in decreasing order of precedence.

Operator	Description
`++ --`	Auto-increment and auto-decrement, both prefix and postfix. `ksh93` only.
`+`	Unary plus. `ksh93` only.
`-`	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 (short-circuit).
`\|\|`	Logical OR (short-circuit).
`?:`	Inline conditional evaluation. `ksh93` only.
`*= /= %=`	Assignment.
`= += -=`
`<<= >>=`
`&= ^= \|=`
`,`	Sequential expression evaluation. `ksh93` only.

4.4.2 Built-in Mathematical Functions (ksh93 only)

ksh93 provides access to the standard set of mathematical functions. They are called using C function call syntax.

Name	Function	Name	Function
`abs`	Absolute value	`log`	Natural logarithm
`acos`	Arc cosine	`sin`	Sine
`asin`	Arc sine	`sinh`	Hyperbolic sine
`cos`	Cosine	`sqrt`	Square root
`cosh`	Hyperbolic cosine	`tan`	Tangent
`exp`	Exponential function	`tanh`	Hyperbolic tangent
`int`	Integer part of floating-point number

4.4.3 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