09-28-2016
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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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)