Bash substitute gives unexpected results (?)

[Johnny Rosenberg]

$ a="Black Sand Beach (ブラック・サンド・ビーチ)"; echo $a | sed 's/[^(|–]//g'
(
$

This is what I want. Everything except ”(” and ”–” (n-dash) should be
removed.
However, using pure Bash doesn't seem to work:

$ a="Black Sand Beach (ブラック・サンド・ビーチ)"; echo ${a//[^(|–]}
(ブラック・サンド・ビーチ
$
Why does Bash consider n-dash and some Japanese characters the same? :-O

Is there a setting I need to do somehow?



Kind regards

Johnny Rosenberg
ジョニー・ローゼンバーグ
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