Promise object for child_process.spawn

What This?

This script generates Promise Object of child_process.spawn.

Why invented?

Using child_process.spawn, ChildProcess is returned, and ChildProcess approach is great for applications that runs in the long term. However, the most applications have command line arguments as inputs, and they output text to stdout / stderr, and then exit the app in the short term. It means ChildProcess seems to have too many functions for "Run and Away" apps (Moreover, gulp handles only stream pipe and Promise objects).

This script generates a Promise object with child_process.spawn and it takes then and catch approach.

Installation

There are 2 ways:

• Running npm install simple-process tries to get the latest stable version and this is the recommended way to get this script.
• Cloning this repo is the secondary way to use this scipt, but its un-stability is the notable point.

How to use

General Purpose

To run apps, using simple-process directly is the most suitable way. i.e. code like this:

(() => {
  'use strict';
  let command = require('simple-process');
  module.exports = () => {
    // Single command use
    command('ls --color=auto').then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    });
    // Multiple commands use
    command([`cd ${__dirname}/src`, 'ls --color=none']).then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    });
    // Handle Error Case
    command(['jugem jugem', 'gokoh no', 'surikire']).then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    }).catch((stats) => {
      if (stats instanceof Error) {
        throw stats
      } else {
        console.log(stats.code, stats.signal, stats.stdout, stats.stderr);
      }
    });
    // Non shell mode. Note that non-shell mode accepts only a single command.
    command('ls', ['--color=auto'], {'shell': false}).then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    });
  };
})();

Python with pyvenv

If you have python apps and want to run them in virtual environment, there's a suitable wrapper in this script: simple-process.pyvenv. To use it, code like this:

(() => {
  'use strict';
  let command = require('simple-process');
  module.exports = () => {
    // Single command
    command.pyvnenv('hello.py').then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    }).catch((stats) => {
      if (stats instanceof Error) {
        throw stats
      } else {
        console.log(stats.code, stats.signal, stats.stdout, stats.stderr);
      }
    });
    // Multiple commands
    command.pyvnenv(['start.py', 'compile.py']).then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    }).catch((stats) => {
      if (stats instanceof Error) {
        throw stats
      } else {
        console.log(stats.code, stats.signal, stats.stdout, stats.stderr);
      }
    });
    // Additional Venv search path
    command.pyvnenv('hello.py', ['vendor/pyvenv', 'myenv']).then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    }).catch((stats) => {
      if (stats instanceof Error) {
        throw stats
      } else {
        console.log(stats.code, stats.signal, stats.stdout, stats.stderr);
      }
    });
    // Overwtite Venv search path
    command.pyvnenv(
      'hello.py', ['vendor/pyvenv', 'myenv'], true
    ).then((result) => {
      console.log(result.stdout);
      console.warn(result.stderr);
    }).catch((stats) => {
      if (stats instanceof Error) {
        throw stats
      } else {
        console.log(stats.code, stats.signal, stats.stdout, stats.stderr);
      }
    });
  };
})();

Note that you can't run pyvenv function with non-shell mode because pyvenv doesn't provide any options to control child_process.spawn while simple-process function provides. i.e. pyvenv always run in shell-mode.

Ruby with bundler

If you have ruby apps and want to run them in bundler's environment, there's a suitable wrapper in this script: simple-process.bundleExec. To use it, code like this:

'use strict';
let command = require('simple-process');
module.exports = () => {
  // Single command
  command.bundleExec('hello.rb').then((result) => {
    console.log(result.stdout);
    console.warn(result.stderr);
  }).catch((stats) => {
    if (stats instanceof Error) {
      throw stats
    } else {
      console.log(stats.code, stats.signal, stats.stdout, stats.stderr);
    }
  });
  // Multiple commands
  command.bundleExec(['start.rb', 'compile.rb']).then((result) => {
    console.log(result.stdout);
    console.warn(result.stderr);
  }).catch((stats) => {
    if (stats instanceof Error) {
      throw stats
    } else {
      console.log(stats.code, stats.signal, stats.stdout, stats.stderr);
    }
  });
};
})();

Contribution

If you found bugs, feel free to create issues at github issues tracker, but sending Pull Requests is more appreciated. When you send Pull Requests, don't forget to add your name to contributors list in package.json.

License (MIT License)

Copyright 2017- Hiroaki Yamamoto

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.