Aritmetika v bash-i
Petr Janda
janda na netbox.cz
Úterý Listopad 7 13:13:42 CET 2006
On Tue, Nov 07, 2006 at 11:39:43AM +0100, Vancl Miroslav (QRIS) wrote:
> Kolega me prakvapil (fungujicim) zapisem typu:
>
> $x=$[$y+1]
>
> tak jsem nelenil a zacal hledat v man bash... a nic jsem nenasel.
> Bud neumim hledat, nebo je to nejaka skryta vlastnost. Nemuzete me nekdo
> navest na popis, pripadne vysvetlit cim se $[ ... ] lisi od $(( ... )) ?
>
> Diky
>
> M. Vancl
>
man bash (muj)
Arithmetic Expansion
Arithmetic expansion allows the evaluation of an arithmetic expression
and the substitution of the result. The format for arithmetic expan-
sion 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 expansion, string expansion,
command substitution, and quote removal. Arithmetic expansions may be
nested.
The evaluation is performed according to the rules listed below under
ARITHMETIC EVALUATION. If expression is invalid, bash prints a message
indicating failure and no substitution occurs.
Takze vlastne nijak, jen $[expression] prestane fungovat :-)
S pozdravem
Petr Janda
--
email: /bin/sh -c 'A=netbox; B=janda; printf "%s@%s.cz\n" ${B} ${A}'
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