shell-source

Source environment variables from a shell script into a Node.js process.

Dragons:

Since sourcing a shell script means actually executing code, it is an unsafe thing to do unless you can 100% guarantee its contents are not rm -rf /. You've been warned!

Why

You have some configuration data stored in a sourcable shell script, but need access to that data from a JavaScript program. You could try to parse the file as text, but that would only work if you could be sure the script does not expand any variables or execute any code.

How

Spawns the process owner's default shell and executes a POSIX compliant wrapper script that in turn sources the file of your choosing. The wrapper then calls env which writes the child process' updated environment to stdout. The parent (Node.js) process can then parse this output and update process.env accordingly.

Example

Consider the (contrived) example below of a script that needs to be executed before its variables can be evaluated in a useful way:

export SERVER_HOST="$(hostname)"
export SERVER_PORT="$(grep -m1 '# HTTP Alternate' < /etc/services | sed 's/[^0-9]*\(.*\)\/.*/\1/')"
export PATH="node_modules/.bin:$PATH"

A Node.js process can then use shell-source to emulate the behavior of sh's . built-in, executing the script before absorbing any enviroment changes it effects:

var source = require('shell-source');

source(__dirname + '/env.sh', function(err) {
  if (err) return console.error(err);

  console.log(process.env.SERVER_HOST); // ::
  console.log(process.env.SERVER_PORT); // 8080
  console.log(process.env.PATH);        // node_modules/.bin:/usr/local/bin
});

Install

$ npm install shell-source

Test

$ npm test

Require

var source = require('shell-source');

Use

source(filepath, [opts,] callback);

• filepath The full path to the shell script that should be sourced.
• opts An options object which can contain:
  • source A boolean. Defaults to true. If set to false, the callback can receive the evironment object as its second argument and process.env will be left unmolested.
  • wrapper Use your own wrapper script. source.sh is used by default.
  • reserved An object to merge with the default blacklist where SHLVL and _ are already set to true.
• callback A callback with signature:

function(err, environment) {
    console.log(err, environment);
}

Notes

Obviously it would be really nice if this could be done synchronously. However, until something like this lands on stable, I'm not sure if there is a sane way to accomplish it. If there is, please let me know.

Releases

The latest stable version is published to npm.

• 1.0.0
• First release.

License

Copyright © 2014 Jesse Tane jesse.tane@gmail.com

This work is free. You can redistribute it and/or modify it under the terms of the WTFPL.

No Warranty. The Software is provided "as is" without warranty of any kind, either express or implied, including without limitation any implied warranties of condition, uninterrupted use, merchantability, fitness for a particular purpose, or non-infringement.