Prock - No Fuss Child Processes

Prock lets you spawn child processes with the ability to listen for standard output, and affords the simplicity of passing a callback like you would with child_process.exec.

const Prock = require("prock");

Prock.init("git status", {
  "cwd": pathToGitRepo
}, (err, stdoutString, stderrString, exitCode, exitSignal) => {
  if (err) {
    return handleError(err);
  }

  // ...
}).on("output", (stdoutputString) => {
  // Data is either from stdout or stderr of the child process
}).on("out", (stdoutString) => {
  // Do something with the output
}).on("err", (stderrString) => {
  // Do something with the error output
});

Or use it like any other class:

const Prock = require("prock");

let Process = new Prock(someCommand, someOptions, someCallback);

Prock instances try to be a drop in replacement for normal ChildProcess objects

They offer all the same event subscriptions, prototype methods, and properties as Node's ChildProcess objects. The only exception is that an error event handler isn't required if a callback is passed to the constructor. In that case, the error will be saved, and passed to the callback. Of course, if you want to subscribe to the error event, you're welcome to.

Use it like child_process.exec

const Prock = require("prock");

Prock.exec("cat someFile.txt", {
  "env": {
    "ENV_VAR": "ENV_VAL" // Completely uneeded in this case, but whatever
  }
}, (err, stdout, stderr, exitCode, exitSignal) => {
  // stdout = the contents of someFile.txt
});

Use it like child_process.spawn

const spawn = require("prock").spawn;
const ls = Prock.spawn("ls", [ "-lh", "/usr" ]);

ls.on("out", (data) => {
  console.log(`stdout: ${data}`);
}).on("err", (data) => {
  console.log(`stderr: ${data}`);
}).on("close", (code) => {
  console.log(`child process exited with code ${code}`);
});

Notes / Limitations

Although Prock lets you pass a string as the command unlike child_process.spawn, it doesn't let you easily redirect IO like you can using child_process.exec.

const Prock = require("prock");

// This won't work
let Proc = new Prock("echo $SOMETHING > out.txt", (error, out, err) => {
	// Pretty much nothing happend, same as trying to do:
	// child_proces.spawn("echo", [ "$SOMETHING", '>', "out.txt" ]);
});

Todo

• [ ] Feature requests welcome
• [ ] Handle IO redirection (>, >>, etc.) - Create multiple Prock instances, and pipe stdio around.

MIT License - Copyright © 2016 Benjamin Leffler