bash中()及{}差別

1. {}中設定的變數會影響全域變數
2. { 必須有空白字元，}前必須有;字元

測試
c=a;echo c=$c;
{ echo "{} $c set {}"; c="set {}";};
(echo "() $c set ()"; c="set ()");
echo c=$c;

c=a;echo c=$c;
(echo "() $c set ()"; c="set ()");
{ echo "{} $c set {}"; c="set {}";};
echo c=$c;