现在开始接手node端测试，有好多知识点，比如启动进程的命令，查看进程的命令都不是很清晰，现在具体来学习下～
npm由来
前端最大的社区是GitHub，大家在这里分享代码，讨论问题，收集学习资源。大家需要依赖什么安装包从以前的去官网下载到去GitHub下载，还是很麻烦。这时候一个拥有三大美德的程序员 Isaac Z. Schlueter （以下简称 Isaaz）给出一个解决方案：用一个工具把这些代码集中到一起来管理吧！
这个工具就是他用 JavaScript （运行在 Node.js 上）写的 npm，全称是 Node Package Manager
NPM 的实现思路大概是这样的：
- 买个服务器作为代码仓库（registry），在里面放所有需要被共享的代码
- 发邮件通知 jQuery、Bootstrap、Underscore 作者使用 npm publish 把代码提交到 registry 上，分别取名 jquery、bootstrap 和 underscore（注意大小写）
- 社区里的其他人如果想使用这些代码，就把 jquery、bootstrap 和 underscore 写到 package.json 里，然后运行 npm install jquery，npm 就会帮他们下载代码
- 下载完的代码出现在 node_modules 目录里，可以随意使用了。
这些可以被使用的代码被叫做「包」（package），这就是 NPM 名字的由来：Node Package(包) Manager(管理器)。node包管理器。
npm的应用
新版的nodejs 已经集成了npm，所以安装nodejs的时候，npm也一并安装好了。
常用命令：
安装模块：npm install <module name>
卸载模块：npm uninstall <module name>
更新模块：npm update <module name>
package.json...
在 NodeJS 项目中，会看到一个package.json，这个文件用来声明项目中使用的模块，这样在新的环境部署时，只要在 package.json 文件所在的目录执行npm install命令即可安装所需要的模块。
还有一些scripts脚本,可以执行一些命令，比如启动npm start
{ "name": "maimai_node", "version": "0.0.0", "private": true, "scripts": { "start": "DEBUG='app,body,rpc' gulp watch", "pc": "DEBUG='app,body,rpc' gulp watch_pc", "test": "DEBUG='app' mocha test/main.js --harmony -t 200000", "dev": "DEBUG='' gulp watch", "reload": "DEBUG='app,body,rpc' node --harmony --inspect app.js", "dev:allocatememory": "DEBUG='app,body,rpc' gulp --max_old_space_size=4098 watch", "growth": "DEBUG='app,body,rpc' gulp --gulpfile gulpfile.growth.js --max_old_space_size=4098 watch", "build-lib": "node-gyp rebuild --directory native_lib", "build-bundle": "webpack --config webpack.config.js --progress --display-optimization-bailout", "lint": "CHANGED_LIST=`git diff-index --name-only HEAD | grep .js$`; if [[ $CHANGED_LIST ]]; then ./node_modules/.bin/eslint --fix `echo $CHANGED_LIST | xargs`; fi", "precommit": "#npm run lint", "watchNoBundle": "DEBUG='app,body' DEV_PATH=dev gulp --max_old_space_size=4098 watchNoBundle" }, "dependencies": { "autoprefixer": "6.0.3", "autoprefixer-core": "6.0.1", "babel": "6.5.2", "babel-eslint": "^8.0.3", "babel-plugin-transform-async-to-generator": "6.8.0", "babel-polyfill": "6.9.1", "babel-preset-es2015": "6.9.0", "babel-preset-react": "6.11.1", "babel-preset-stage-0": "6.5.0", "babel-register": "6.9.0", "babelify": "6.4.0", "baobab": "2.0.1", "base62": "1.1.0", "bindings": "1.2.1", "blob-util": "2.0.2", "bluebird": "3.0.5", "brfs": "1.4.1", "bunyan": "1.8.2", "canvas": "1.6.5", "classnames": "^2.1.3", "co": "4.6.0", "co-child-process": "0.0.3", "co-mocha": "1.1.2", "co-request": "1.0.0", "co-wechat-api": "3.8.2", "co-wechat-oauth": "2.0.1", "commander": "2.9.0", "crc-32": "1.0.1", "crypto-js": "^3.1.9-1", "cssmin": "0.4.3", "cuint": "0.2.0", "date-utils": "1.2.17", "debug": "2.2.0", "detect-browser": "1.1.1", "dtrace-provider": "0.8.5", "echarts": "^4.0.4", "echarts-for-react": "^2.0.8", "email-validation": "0.1.2", "emoji-strip": "^1.0.1", "envify": "3.4.0", "es6-promise": "3.0.2", "event-stream": "3.3.2", "eventemitter3": "^3.1.0", "exenv": "^1.2.2", "fastclick": "^1.0.6", "find-remove": "1.0.1", "form-data": "1.0.1", "generic-pool": "2.2.0", "gulp": "3.9.1", "gulp-cssmin": "0.1.7", "gulp-download": "0.0.1", "gulp-imacss": "1.0.0", "gulp-jade": "1.1.0", "gulp-less": "3.0.3", "gulp-nodemon": "2.0.4", "gulp-postcss": "6.0.1", "gulp-rename": "1.2.2", "gulp-replace": "0.5.4", "gulp-streamify": "1.0.2", "gulp-uglify": "1.4.2", "gulp-util": "3.0.6", "gulp-watch": "4.3.5", "gulp-zip": "3.1.0", "heapdump": "0.3.7", "highcharts": "^6.0.7", "hls.js": "0.8.6", "html2canvas": "^1.0.0-alpha.12", "http-shutdown": "1.2.0", "idcard": "4.1.0", "imacss": "1.0.0", "immutability-helper": "^2.9.0", "in-view": "0.6.0", "ioredis": "2.3.0", "iscroll": "5.2.0", "jade": "1.11.0", "jade-loader": "0.8.0", "jquery": "^3.3.1", "js-base64": "2.3.2", "json-loader": "0.5.4", "jsonfile-promised": "0.0.1", "jsonwebtoken": "5.4.0", "klass": "1.4.1", "koa": "1.2.4", "koa-body": "1.4.0", "koa-compose": "2.4.0", "koa-cors": "0.0.16", "koa-csrf": "2.3.0", "koa-gzip": "0.1.0", "koa-jade": "2.0.0", "koa-mount": "1.3.0", "koa-proxy": "0.4.1", "koa-qs": "2.0.0", "koa-rewrite": "1.1.0", "koa-router": "5.2.3", "koa-send": "3.1.0", "koa-session": "3.3.1", "koa-static": "1.4.9", "koa-swig": "2.1.0", "koa-views": "3.1.0", "lodash": "^4.17.10", "md5": "^2.2.1", "md5-file-promise": "1.0.2", "mobile-detect": "1.3.1", "mocha": "2.3.3", "modern-syslog": "^1.1.4", "moment": "2.10.6", "moment-mini": "2.18.1", "mongoose": "4.4.12", "mongoose-auto-increment": "5.0.1", "mongoose-multitenant": "0.8.2", "ms": "0.7.1", "mysql": "2.14.1", "nan": "2.6.2", "nconf": "0.8.2", "node-canvas-text": "1.0.2", "node-fetch": "1.7.1", "node-jsx": "0.13.3", "node-rsa": "0.2.26", "node-xml-lite": "0.0.5", "nsqjs": "0.8.4", "opentype.js": "0.7.1", "pako": "0.2.8", "platform": "^1.3.4", "preload-js": "^0.6.3", "prop-types": "15.6.0", "protobufjs": "6.8.0", "qiniu": "7.2.1", "qrcode.react": "^0.8.0", "qs": "6.5.1", "radium": "^0.14.2", "rapscallion": "^2.1.14", "ratelimiter": "2.0.1", "raven": "2.2.1", "raw-body": "2.1.4", "raw-loader": "0.5.1", "react": "^15.6.1", "react-addons-linked-state-mixin": "15.6.0", "react-addons-pure-render-mixin": "15.6.0", "react-autosuggest": "^9.3.4", "react-bootstrap": "0.31.0", "react-clipboard.js": "^1.1.3", "react-countup": "^3.0.3", "react-distpicker": "^1.0.1", "react-dom": "15.6.1", "react-fastclick": "^3.0.2", "react-fullpage": "^0.1.18", "react-helmet": "2.1.1", "react-highcharts": "^16.0.2", "react-id-swiper": "^1.6.8", "react-infinite": "0.11.0", "react-infinite-scroller": "1.0.13", "react-iscroll": "2.0.3", "react-lazyload": "^2.3.0", "react-motion": "0.5.0", "react-radio-group": "^3.0.3", "react-scroll": "^1.7.10", "react-side-effect": "1.0.2", "react-slick": "^0.22.3", "react-sticky": "5.0.0", "react-swipe": "3.0.0", "react-swipeable-views": "^0.12.4", "react-swipeable-views-core": "^0.12.11", "react-swipeable-views-utils": "^0.12.13", "react-tap-event-plugin": "^2.0.1", "react-tappable": "^1.0.4", "react-timer-mixin": "0.13.3", "react-transition-group": "^2.3.1", "redis": "2.7.1", "request": "2.65.0", "retry": "0.8.0", "rmc-picker": "^5.0.5", "rmc-pull-to-refresh": "^1.0.11", "routes": "2.1.0", "save": "^2.3.2", "semver": "5.0.3", "simditor": "2.3.6", "sphinxapi": "1.1.1", "style-loader": "0.13.1", "styled-components": "^3.4.10", "superagent": "3.5.2", "swig": "1.4.2", "swipe-js-iso": "2.0.1", "tiny-cookie": "0.5.4", "truncate": "2.0.0", "underscore": "1.8.3", "underscore.string": "3.2.2", "unicode": "^0.6.1", "url-loader": "^1.1.2", "urlsafe-base64": "1.0.0", "uuid": "2.0.1", "vinyl-source-stream": "1.1.0", "watchify": "3.6.1", "webpack-stream": "3.2.0", "weixin-js-sdk": "1.2.0", "weixin-pay": "1.1.6", "whatwg-fetch": "0.10.0", "zepto-webpack": "1.2.1" }, "devDependencies": { "aliasify": "2.0.0", "babel-core": "6.26.0", "babel-loader": "7.1.2", "babel-preset-env": "1.6.1", "colors": "^1.2.1", "css-loader": "0.28.4", "eslint": "^4.13.0", "eslint-plugin-react": "^7.5.1", "gulp-imagemin": "^4.1.0", "gulp-plumber": "^1.2.0", "happypack": "^4.0.0", "hard-source-webpack-plugin": "0.11.1", "husky": "^0.14.3", "less": "^2.5.3", "less-loader": "^4.1.0", "react-tappable": "^1.0.4", "stylelint": "^9.9.0", "webpack": "3.10.0", "webpack-bundle-analyzer": "2.8.2", "webpack-livereload-plugin": "^1.2.0", "webpack-merge": "4.1.1" } }
启动：npm start 就是执行 DEBUG='app,body,rpc' gulp watch
重启：npm restart
停止：npm stop
有时候采用上面的方式启动node服务时，会报out of memory的错。那么我们可以用下面的命令。
npm run dev:allocatememory 就如package.json所写，最大化内存。
我们还经常看见cnpm，这个是淘宝镜像。
由于国内连npm服务是比较慢的，所以淘宝就自己出了一个镜像，同步频率是10分钟一次，保证package跟npm一致。
$ npm install -g cnpm --registry=https://registry.npm.taobao.org
安装后就可以cnpm代替npm了。比如：cnpm install <module name>
pm2是什么
PM2(process manager)是node进程管理工具,可以利用它来简化很多node应用管理的繁琐任务，如性能监控、自动重启、负载均衡等
常见命令：
$ npm install pm2 -g # 命令行安装 pm2
$ pm2 start app.js -i 4 #后台运行pm2，启动4个app.js
# 也可以把'max' 参数传递给 start
# 正确的进程数目依赖于Cpu的核心数目
$ pm2 start app.js --name my-api # 命名进程
$ pm2 list # 显示所有进程状态
$ pm2 monit # 监视所有进程
$ pm2 logs # 显示所有进程日志
$ pm2 stop all # 停止所有进程
$ pm2 restart all # 重启所有进程
$ pm2 reload all # 0秒停机重载进程 (用于 NETWORKED 进程)
$ pm2 stop 0 # 停止指定的进程
$ pm2 restart 0 # 重启指定的进程
$ pm2 startup # 产生 init 脚本 保持进程活着
$ pm2 web # 运行健壮的 computer API endpoint (http://localhost:9615)
$ pm2 delete 0 # 杀死指定的进程
$ pm2 delete all # 杀死全部进程
运行进程的不同方式：
$ pm2 start app.js -i max # 根据有效CPU数目启动最大进程数目
$ pm2 start app.js -i 3 # 启动3个进程
$ pm2 start app.js -x #用fork模式启动 app.js 而不是使用 cluster
$ pm2 start app.js -x -- -a 23 # 用fork模式启动 app.js 并且传递参数 (-a 23)
$ pm2 start app.js --name serverone # 启动一个进程并把它命名为 serverone
$ pm2 stop serverone # 停止 serverone 进程
$ pm2 start app.json # 启动进程, 在 app.json里设置选项
$ pm2 start app.js -i max -- -a 23 #在--之后给 app.js 传递参数
$ pm2 start app.js -i max -e err.log -o out.log # 启动 并 生成一个配置文件
你也可以执行用其他语言编写的app ( fork 模式):
$ pm2 start my-bash-script.sh -x --interpreter bash
$ pm2 start my-python-script.py -x --interpreter python