# shell

## code style

```
缩进为两个空格
if [condition]; then # ;then写在一行
while condition; do # ;then写在一行
```

## 以一下脚本为例

* 模块化

    . ./utils.sh # 或者 source./utils.sh

  ```
             # 为了模块化
             # 是导入当前目录下的utils.sh脚本
  ```
* function 传参数 参数使用$num代表传入的参数

  return 听说智能返回数字(c语言里面的状态码) 因此想返回字符串使用echo
* 函数调用 单行调用直接使用func\_name; 如果在echo或者赋值的时候，使用$() 例如: echo $(date +%Y-%m-%d) A=echo $(date +%Y-%m-%d)
* if 不等时加! 例如: if \[ ! "$1" ]; then abc fi
* 脚本提示

## 例子

```
#!/bin/bash
. ./utils.sh

path=${PWD}"/../"

today(){
    echo $(date +%Y-%m-%d)
}

yesterday(){
    echo $(date -d yesterday +%Y-%m-%d)
}

scrapy_data(){
  start_date=$1
  end_date=$2
  cd $path
  echo "log: scrapy ${start_date} ~ ${end_date} data"
  scrapy crawl paper_edu_spider -a start_date=$start_date -a end_date=$end_date
}

scrapy_today(){
  scrapy_data $(today) $(today);
}

scrapy_yesterday(){
  scrapy_data $(yesterday) $(yesterday);
}

if [ ! "$1" ]; then
  echo "-h for help"
  exit 1
fi

while getopts "hty" arg; do
  case $arg in
    t)
      scrapy_today;
      ;;
    y)
      scrapy_yesterday;
      ;;
    h)
      echo "usage:"
      echo "    use -t to scrapy today"
      echo "    use -y to scrapy yesterday"
      ;;
    ?)
      echo "-h for help"
      exit 1
      ;;
  esac
done
```

## 将某个目录下的某类型的文件都搞到一个文件中

例如将所有的py文件copy到一个文件中(例如我想在kindle里面看python-pattern这个项目的所有源代码)

下面的命令将项目里面所有的文件按照文件名+内容的方式copy到了pattern.txt中

for f in `ls *py`;do echo $f >> pattern.txt; cat $f >> pattern.txt;done;

## bash的{}扩展

{}中使用','分隔会自动扩展

```
cp xxx/{a,b} --> cp xxx/a xxx/b
```

## 判断是否存在

注意if时 \[ ]左右都要有空格

判断文件夹

```
if [ -d /opt/python_env/duoduo369 ];then
```

判断文件

```
if [ -e /run/duoduo369-supervisord.pid ] ;then
```


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