javascript - Attempting synchronous behaviour with shell script execution in node.js -

i'm quite new node.js , i'm using server receive http.get requests browser, processing , return result browser.

the processing scraping website using phantom.js/casper.js , because of complications using casper.js in node.js i'm executing sub-process use of shell script.

when run code below , make request browser, response seems appear before shell script has run. tried using async library run steps in series run.sh runs , returns value before it's added response doesn't seem work that. can spot stupid mistake?

thanks in advance!

var express = require('express'); var app = express(); var sys = require('sys'); var exec = require('child_process').exec; var async = require('async'); var auth = express.basicauth('test', 'pass'); var server = app.listen(3000, function() {     console.log('listening on port %d', server.address().port); }); var result;   //app.use(auth);  app.get('/free/:u/:p', auth, function(req, res) {      async.series([         function(callback){             var puts = function (error, stdout, stderr) {                 result = stdout;              }              exec("./run.sh " + req.params.u + " " + req.params.p, puts);              callback(null);         },         function(callback){              res.writehead(200,{'content-type':'application/json'});              res.send(result)              callback(null);         }     ]); });  app.get('/', function(req, res) {   res.send('hello!'); }); 

you're not calling callback(null) asynchronously. need put in puts.

also, shouldn't use global results variable (it's global across requests, possibly leaking data different clients - arghh!). , there's hardly reason use async.js trivial chain.

app.get('/free/:u/:p', auth, function(req, res) {      exec("./run.sh " + req.params.u + " " + req.params.p, function (error, stdout, stderr) {        res.writehead(200,{'content-type':'application/json'});        res.send(stdout);     }); }); 

notice security issue introduced not escaping shell parameters.