node.js - Behavior difference between `exec` and `spawn` -


i'm attempting create child process running mongo shell command-line arguments clone database. code functions correctly using child_process.exec(...), not child_process.spawn(...). improved security, i'd prefer use the latter.

i'm on macos 10.11.6, using mongo shell version 3.2.6 installed via brew.

uname -a

darwin blackknight 15.6.0 darwin kernel version 15.6.0: mon aug 29 20:21:34 pdt 2016; root:xnu-3248.60.11~1/release_x86_64 x86_64

mongo --version

mongodb shell version: 3.2.6

ls -la which mongo

lrwxr-xr-x 1 daldridge wheel 33 jul 29 09:32 /usr/local/bin/mongo -> ../cellar/mongodb/3.2.6/bin/mongo

here's sample source:

const async = require('async'); const exec = require('child_process').exec; const spawn = require('child_process').spawn;  function _getcreateargs(name) {   return [     '--verbose',     'localhost:27017/admin',     `--eval="db.getsiblingdb('${name}').createcollection('${name}');"`,   ]; }  function _getcloneargs(source, target) {   return [     '--verbose',     'localhost:27017/admin',     `--eval="db.copydatabase('${source}', '${target}');"`,   ]; }  function _childhandler(child, callback) {   child.stderr.on('data', (data) => { console.log(data.tostring()); });   child.stdout.on('data', (data) => { console.log(data.tostring()); });   child.on('exit', (exitcode) => {     callback(exitcode ? new error(`mongo database clone - unexpected exit code: ${exitcode}`) : null, null);   }); }  function _createdatabase(database, callback) {   const child = exec(`mongo ${_getcreateargs(database).join(' ')}`);   _childhandler(child, callback); }  function _cloneviaexec(source, target, callback) {   const child = exec(`mongo ${_getcloneargs(source, target).join(' ')}`);   _childhandler(child, callback); }  function _cloneviaspawn(source, target, callback) {   const child = spawn('mongo', _getcloneargs(source, target));   _childhandler(child, callback); }  const databasename = `${date.now()}`; async.waterfall([   (waterfallcallback) => {     _createdatabase(databasename, waterfallcallback);   },    (waterfallcallback) => {     async.series(async.reflectall([       // 1 works       (seriescallback) => { _cloneviaexec(databasename, 'cloneviaexec', seriescallback); },        // 1 doesn't       (seriescallback) => { _cloneviaspawn(databasename, 'cloneviaspawn', seriescallback); },     ]), waterfallcallback);   }, ], (error) => {   if (error) { console.log(error); } });

the database , collection creations succeed (using exec), first copy attempt (also using exec), equivalent clone via spawn not work. there nothing on stderr child.

ideas?


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