我使用npm作为构建工具，我的脚本部分看起来像：
"scripts": {
"clean": "rm './build/+(css|js)/*'",
"watch:js": "watch 'npm run build:js' ./app/js",
"prebuild:js" : "rimraf ./build/js && mkdirp ./build/js",
"build:js": "browserify ./app/js/app.js -t [ babelify --presets es2015 ] -d | exorcist ./build/js/bundle.js.map | uglifyjs -c > ./build/js/bundle.js",
"watch:css": "watch 'npm run build:css' ./app/stylesheets",
"prebuild:css" : "rimraf ./build/css && mkdirp ./build/css",
"build:css": "cssimport ./app/stylesheets/app.css | cssmin > ./build/css/bundle.css",
"build": "npm run build:js && npm run build:css",
"build:watch": "parallelshell 'npm run watch:js' 'npm run watch:css'",
"watch:node": "nodemon ./app/server.js",
"start:dev": "npm run build:watch && npm run watch:node",
"start:prod": ""
},
现在，当我更改./app/js中的js文件时，(pre)build:js会成功执行一次。
但是当我在./app/stylesheets中更改css文件时，(pre)build:css执行了三次，成功了吗？！
输出如下：
myapp@0.0.1 prebuild：css / home / me / dev / myapp rimraf ./build/css& amp ;& amp; mkdirp ./build/css
myapp@0.0.1 build：css / home / me / dev / myapp cssimport ./app/stylesheets/app.css | cssmin＆gt; ./build/css/bundle.css
myapp@0.0.1 prebuild：css / home / me / dev / myapp rimraf ./build/css& amp ;& amp; mkdirp ./build/css
myapp@0.0.1 build：css / home / me / dev / myapp cssimport ./app/stylesheets/app.css | cssmin＆gt; ./build/css/bundle.css
myapp@0.0.1 prebuild：css / home / me / dev / myapp rimraf ./build/css& amp ;& amp; mkdirp ./build/css
myapp@0.0.1 build：css / home / me / dev / myapp cssimport ./app/stylesheets/app.css | cssmin＆gt; ./build/css/bundle.css
我不明白为什么会这样做，我尝试使用cssimport和cssmin的替代品，但同样的情况也会发生。
更新
我将parallelshell替换为concurrently，现在当我在运行时更改css时，我得到：
[1]
[1]＆gt; myapp@0.0.1 prebuild：css / home / me / myapp
[1]＆gt; rimraf ./build/css& amp ;& amp; mkdirp ./build/css
[1]
[1]
[1]＆gt; myapp@0.0.1 build：css / home / me / myapp
[1]＆gt; cssimport ./app/stylesheets/app.css | cssmin＆gt; ./build/css/bundle.css
[1]
myapp@0.0.1 prebuild：css / home / me / myapp rimraf ./build/css& amp ;& amp; mkdirp ./build/css
myapp@0.0.1 build：css / home / me / myapp cssimport ./app/stylesheets/app.css | cssmin＆gt; ./build/css/bundle.css
myapp@0.0.1 prebuild：css / home / me / myapp rimraf ./build/css& amp ;& amp; mkdirp ./build/css
myapp@0.0.1 build：css / home / me / myapp cssimport ./app/stylesheets/app.css | cssmin＆gt; ./build/css/bundle.css
所以似乎在css任务watch:css之外（[1]）build:css任务执行两次以上，但我只用concurrently执行任务，那怎么能在concurrently ??