exec-promise: Promise wrapper around child_process.exec

exec-promise.js

const childProcess = require('child_process');

// otherwise we get a stupid warning.
process.stdout.setMaxListeners(100);
process.stderr.setMaxListeners(100);

/**
 * Promisified child_process.exec
 *
 * @param cmd
 * @param opts See child_process.exec node docs
 * @param {stream.Writable} opts.stdout If defined, child process stdout will be piped to it.
 * @param {stream.Writable} opts.stderr If defined, child process stderr will be piped to it.
 * @param {bool} opts.killOnExit Kill the child process when the parent process exits
 *
 * @returns {Promise<{ stdout: string, stderr: stderr }>}
 */
function execp(cmd, opts) {
	opts || (opts = {});
	return new Promise((resolve, reject) => {

		const child = childProcess.exec(cmd, opts,
			(err, stdout, stderr) => err ? reject(err) : resolve(stdout.toString('utf8')));

		if (opts.stdout) {
			child.stdout.pipe(opts.stdout);
		}
		if (opts.stderr) {
			child.stderr.pipe(opts.stderr);
		}

		// Kill child on exit
		const killChild = () => {
			child.kill();
		};
		process.setMaxListeners(20);
		process.on('exit', killChild);
		child.on('exit', () => process.removeListener('exit', killChild));
	});
}

exec-promise.ts

import * as childProcess from 'child_process';
import * as stream from 'stream';

// otherwise we get a stupid warning.
process.stdout.setMaxListeners(100);
process.stderr.setMaxListeners(100);

interface IOptions {
  stdout?: stream.Writable,
  stderr?: stream.Writable,
  killOnExit?: boolean
}

function execp(cmd:string, opts:IOptions = {}):Promise<string> {
  return new Promise((resolve, reject) => {

    const child = childProcess.exec(cmd, opts,
      (err, stdout, stderr) => {
        err ? reject(err) : resolve(stdout)
      });

    if (opts.stdout) {
      child.stdout.pipe(opts.stdout);
    }
    if (opts.stderr) {
      child.stderr.pipe(opts.stderr);
    }

    // Kill child on exit
    const killChild = () => child.kill();
    process.setMaxListeners(20);
    process.on('exit', killChild);
    child.on('exit', () => process.removeListener('exit', killChild));
  });
}

export default execp;