let evaluate arithmetic expressions	KornShell Built-in
	SYNOPSIS DESCRIPTION EXAMPLE DIAGNOSTICS PORTABILITY NOTE SEE ALSO

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SYNOPSIS

let expression...

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DESCRIPTION

In the KornShell let evaluates each arithmetic expression from left to right with normal algebraic precedence (multiplication before addition, for example). let uses long integer arithmetic with no checks for overflow. No output is generated; the exit status is 0 if the last expression has a non-zero value and 1 otherwise.

If you issue the command

set -o korn

the line

let "expression"

can also be expressed as

((expression))

This form avoids quoting and enhances readability.

The portable way to write these commands is to use the POSIX command:

: $((expression))

Expressions consist of named variables, numeric constants and operators.

See Arithmetic Substitution in sh for syntax of expressions.

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EXAMPLES

The commands

let a=7 'b=4*2' c=b+1
echo $a $b $c

produce

7 8 9

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DIAGNOSTICS

Possible exit status values are:

0

The last argument evaluated to a non-zero value.

1

The last argument evaluated to a zero value, or the expression contained a syntax error or tried to divide by zero.

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PORTABILITY

let is built into the KornShell on UNIX systems and is not a Bourne Shell command.

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NOTE

This command is built into the MKS KornShell.

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SEE ALSO

Commands:

expr, sh, test