linux shell中 出现select not found问题

#!/bin/sh
echo "You choice?"
select var in "a" "b" "c";do
break;
done
echo $var

运行时出现：

select.sh: 3: select: not found

select.sh: 5: Syntax error: "done" unexpected

把#!/bin/sh改为#!/bin/bash

执行脚本时将sh select.sh改为 bash select.sh