shell判断文件/目录是否存在

https://www.cnblogs.com/37yan/p/6962563.html

caution!!! if should be end with fi

caution!!! there should be a space between [ and ! , also between 1 and ]

if [ ! $# -eq 1  ];then

#!/bin/bash
# 判断传入的参数的个数是不是一个
if [ ! $# -eq   ];then
  echo param error!
  exit
fi

# 判断目录是不是已经存在，如果不存在则创建，存在则输出“dir exist”
dirname=$
echo "the dir name is $dirname"
if [ ! -d $dirname  ];then
  mkdir $dirname
else
  echo dir exist
fi