Only Get Stderr from Exec

[360disrupt]

I have the opposite problem to:
#92

On my local machine with nodemon everything works fine. On the server exec only gives me stderr and the code (which is 0 which equals no error).

I'm using node v.5.0.0. And it is started with pm2 on the server.

I actually don't know if this is a bug or maybe s.th. with the server config.

[nfischer]

Hmmm... this seems like a strange issue. I don't think this is a bug with shelljs, since it seems to work on your local machine. Are you checking the .stdout attribute? .output is deprecated (and will be removed soon).

[360disrupt]

The coffee gets compiled first by gulp before shelljs runs.

executeCommands = (commands, callback)->
  commandsToExecute = ""

  for command in commands
    commandsToExecute += "#{command} && "

  commandsToExecute += "echo \"finished\""

  shell.exec commandsToExecute, (code, stdout, stderr) ->
    logger.info "Exit code: #{code}", stdout
    logger.warn "Program stderr:", stderr
    err = if stderr? && stderr != "" then stderr else null
    return callback err, stdout, code

• commands is an array of shell commands
• callback is my callback to express

e.g. a route:

  app.get('/mongodump', routesService.loggedIn, routesService.cleanParams, (req, res) ->
    shellService.mongoDump req.user, (err, out, code) ->
      return res.json({err: err}) if err?
      return res.json({"out": out, "code": code})
  )

The weird thing is,t hat it makes a complete dump, there is no file missing. The rest of the message is pretty much the same and does not really indicate an error.I just noticed now, that there is the echo finished missing on the server. Could this be related to chaining the commands with &&, then I would rather use async.eachSeries to execute the commands.

If you tell me, that this is not related to shelljs I would transfer this issue to Stackoverflow.

[360disrupt]

PS:
Same thing with async instead of chaining:

executeCommands = (commands, callback)->
  commandEchoFinished = "echo \"finished\""
  commands.push({"name": "commandEchoFinished", "command": commandEchoFinished})
  results = []
  async.eachSeries commands,
    (command, next)->
      shell.exec command.command, (code, stdout, stderr) ->
        logger.info "Command: #{command.name}, exited with code: #{code}", stdout
        logger.warn "Command: #{command.name}", stderr
        err = if stderr? && stderr != "" then stderr else null
        return next err if err?
        results.push({"command":command.name, "code":code, "stdout":stdout})
        return next null
    (err)->
      return callback err if err?
      return callback null, results

[nfischer]

@360disrupt What if you chain the statements with ; instead of &&? Or what if you put echo 'Hello world' as the first command? That would check if it's because of a command failing toward the end.

[jeroenransijn]

I am having a similar issue, what is your environment. I am currently using Electron with ShellJS. Also I am Webpack, no idea if this is relevant.

[360disrupt]

I can't really say what it was. It works now, I guess the provider of the server may have changed something. My environment is nodejs 5.0.0.

[nfischer]

@jeroenransijn @360disrupt if either of you have the time to help figure out the bug, that would be much appreciated. I suspect it's due to differences in your environment (we list the supported nodejs and iojs versions in the README, anything outside of that we'll need help supporting).

Thanks!

[jeroenransijn]

@nfischer I was actually not well researched on what I was trying to do. Exec, even with the async option, waits for the process to finish and then gives you back the result of your command. I ended up using require('child_process').spawn() straight from node, which gives you a stream. I was wondering why there is no alternative in ShellJS?

[nfischer]

It returns the child process, so you can use that to access stdout or stderr.

I think this should work:

var c = exec('cmd', {async: true});
c.stdout.on('data', function(stdout) {
  // do something with this chunk of data
});

[360disrupt]

I will use shelljs in another project soon. If I see the problem again I can investigate. Currently I'm not able to look into it because it disappeared.

[nfischer]

I will use shelljs in another project soon. If I see the problem again I can investigate. Currently I'm not able to look into it because it disappeared.

@360disrupt if you can figure out what the issue is, please ping this thread again (or open a new issue). Thanks!

[nfischer]

@360disrupt @jeroenransijn were either of you able to identify the source of the issue?

[nfischer]

We did a big exec refactor, so I'm assuming this is no longer relevant. Holler if this issue comes back.