A $(( expression )) bug? Post: 302982332

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Top Forums UNIX for Advanced & Expert Users A $(( expression )) bug? Post 302982332 by RudiC on Wednesday 28th of September 2016 05:13:59 AM

09-28-2016

Registered User

The

Quote:

Arithmetic Expansion
Arithmetic expansion allows the evaluation of an arithmetic expression and the substitution of the result. The format for arithmetic expansion is:

$((expression))

The old format $[expression] is deprecated and will be removed in upcoming versions of bash.

The expression is treated as if it were within double quotes, but a double quote inside the parentheses is not treated specially. All tokens in the expression undergo parameter and variable expansion, command substitution, and quote removal.

(c.f. man bash) is available in recent shells only, not in sh. As you can see, variable expansion is done implicitly, no $ nor ${} necessary. Your message above is informative, not an error.

Last edited by RudiC; 09-28-2016 at 01:40 PM.. Reason: added the man bash reference

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LEARN ABOUT LINUX

let

let(1)                                                             User Commands                                                            let(1)

NAME

       let - shell built-in function to evaluate one or more arithmetic expressions

SYNOPSIS

   ksh
       let arg...

DESCRIPTION

   ksh
       Each arg is a separate "arithmetic expression" to be evaluated.

EXIT STATUS

       The following exit values are returned:

       0        The value of the last expression is non-zero.

       1        The value of the last expression is zero.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       +-----------------------------+-----------------------------+
       |Availability                 |SUNWcsu                      |
       +-----------------------------+-----------------------------+

SEE ALSO

       ksh(1), set(1), typeset(1), attributes(5)

SunOS 5.10                                                          15 Apr 1994                                                             let(1)

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