betterdownload.sh: 42: betterdownload.sh: Syntax error: "(" unexpected

**将betterdownload.sh放到另外一台虚拟机上下载，有如下错误：
betterdownload.sh: 42: betterdownload.sh: Syntax error: “(” unexpected**

跟踪后打印如下：

root@ubuntu:/home/liufei/pms# sh -x betterdownload.sh + target_dir=default_git+ [ 0 -eq 1 ]+ echo create target folder:default_gitcreate target folder:default_git+ mkdir -p default_git+ rm -rf default_git/*+ cd default_gitbetterdownload.sh: 42: betterdownload.sh: Syntax error: "(" unexpected

网上找度娘后解决：

ehco $SHELL/bin/bash

将脚本的第一句：

#!/bin/sh修改为#!/bin/bash