在node.js中运行串行操作
我有一个并行执行一些shell命令的asynchronous函数
require("fs").readdir("./", function (error, folders) { // asynched require("underscore")._(folders).each(function (folder, folderKey, folderList) { // asynched r("child_process").exec("ls ./" + folder, function(error, stdout, stderr) { console.log("Cant put it here") // Will be run after the first execution is completed }) console.log("Cant put it here either") // Will be run immediately before any execution is completed }) console.log("Cant put it here either") // Will be run immediately before any execution is completed }) 我想在执行这些shell命令后执行某些操作，但是我无法弄清楚如何在asynchronous库中执行此操作。 这些shell命令是并行执行的，所以在执行所有的命令之后 ，没有办法注册执行的处理程序。
有任何想法吗？
更新
在你编辑你的问题以显示你的实际代码后，这应该工作：
var ps = require('child_process'); var fs = require('fs'); var _ = require("underscore"); function listDirectory(dir, callback) { fs.readdir(dir, function (error, folders) { // simply keep track on how many of the ls's have finished var count = folders.length, done = 0; _(folders).each(function (folder, folderKey, folderList) { ps.exec("ls ./" + folder, function(error, stdout, stderr) { console.log('one more done'); done++; if (done === count) { callback(); } }); }); }) } listDirectory('./', function() { console.log('all done!'); });
运行时：
one more done one more done one more done one more done one more done one more done one more done one more done one more done one more done one more done one more done all done!
老答案
我想你使用的是child_process模块。
你需要创build一个包装你的命令。
var spawn = require('child_process').spawn; // this function will execute all the things in the cmds array // after all the processes have exited, it will call the callback function multiSpawn(cmds, callback) { var count = cmds.length; var done = 0; for(var i = 0; i < count; i++) { // spawn the process, modify this if you need to hook up further events // you could also pass in further functions to setup each spawn var ps = spawn(cmds[i].shift(), cmds[i]); ps.on('exit', function() { done++; // keep track on how many commands have finished if (done === count) { callback(); } }); } } multiSpawn([ ['ls', '/usr/lib', '-l'], ['sleep', '1'], // this will sleep 1 seconds ['ls', '/usr/share', '-a'] ], function() { console.log('all done'); });
这将运行所有的3个命令，两个ls将立即完成， sleep将延迟一切1秒，然后callback被调用。
我想这对于期货来说也是可能的，但在这种情况下，这很可能是过度的。
使用async.js库： https ： //github.com/caolan/async
var fs = require('fs'); var async = require('async'); var exec = require('child_process').exec; fs.readdir("./", function (error, folders) { async.forEach(folders, function (folder, callback) { exec("ls ./" + folder, function (error, stdout, stderr) { callback(); }); }, function (error) { // this is called after all shell commands are complete }) });