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_git
create target folder:default_git
+ mkdir -p default_git
+ rm -rf default_git/*
+ cd default_git
betterdownload.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