gpestana / pipe-args

POSIX compliant pipe argument parser for node CLI apps

pipe-args

pipe-args adds support for unix piped arguments to your node CLI apps

pipe-args makes your node CLI apps to fully support unix pipelines, completely out of the box. Require the the pipe-args module and all the piped arguments are added to the process stdin transparently. It also integrates well with popular command line interface/parsers like yarg and commander.js.

Installation

$ npm install --save pipe-args

Usage

#!/usr/bin/env node

const pipe = require('pipe-args').load();
console.log(`The piped arg is ${process.argv[2]}`);

$ echo test | node index.js

$ The piped arg is test

Options

You can define which commands allow the stdin to be copied to process.argv by passing them in the options object:

#!/usr/bin/env node

const pipe = require('pipe-args').load(['command']);
console.log(`The piped arg is ${process.argv[2]}`);

$ echo OK | node command index.js

$ The piped arg is OK

$ echo OK | node commandNotPiping index.js

$ The piped arg is null // stdin was not parsed into process.argv

Integrations

pipe-args plays along with optstrings parsers such as yarg. The following yargs parser code:

#!/usr/bin/env node

const pipe = require('pipe-args').load();
const yargs = require('yargs')

const cli = yargs.demand(1)

console.log(cli.argv);

parses linux-style piped arguments as expected:

$ echo piped_arg | yargs-cli.js

$ { _: [ 'piped_arg' ], '$0': 'index.js' }

License:

MIT © Gonçalo Pestana

pipe-args's Issues

Error: ENXIO: no such device or address, open '/dev/stdin'

ENXIO uncaught exception. This might be related with file descriptions being sockets and not pipes.

Error: ENXIO: no such device or address, open '/dev/stdin'
    at Error (native)
    at Object.fs.openSync (fs.js:549:18)
    at Object.fs.readFileSync (fs.js:397:15)
    at Object.module.exports.load (/home/travis/build/ipfs/js-ipfs/node_modules/pipe-args/index.js:10:27)
    at Object.<anonymous> (/home/travis/build/ipfs/js-ipfs/src/cli/bin.js:5:22)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Function.Module.runMain (module.js:441:10)

  Error: Command failed: /home/travis/build/ipfs/js-ipfs/src/cli/bin.js object data QmZZmY4KCu9r3e7M2Pcn46Fc5qbn6NpzaAGaYb22kbfTqm
  /home/travis/build/ipfs/js-ipfs/node_modules/pipe-args/index.js:13
      if (e.code != 'EAGAIN') throw e;

More info: https://travis-ci.org/ipfs/js-ipfs/jobs/210148607
Related: nodejs/node-v0.x-archive#3530

Unhandled exception (Error: EAGAIN: resource temporarily unavailable, read)

In some cases there is an unhandled EAGAIN exception being thrown. This seems to happen when there is no data in /dev/stdin. I'd expect this to happen only when in async mode though.

Error: EAGAIN: resource temporarily unavailable, read
    at Error (native)
    at Object.fs.readSync (fs.js:603:19)
    at Object.fs.readFileSync (fs.js:438:24)
    at /Users/home/dev/js-ipfs/node_modules/pipe-args/index.js:7:31
    at Object.<anonymous> (/Users/home/dev/js-ipfs/node_modules/pipe-args/index.js:9:3)
    at Module._compile (module.js:409:26)
    at Object.Module._extensions..js (module.js:416:10)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Module.require (module.js:353:17)

feat: Copy stdin to process.argv only in certain cases

In some cases, there might be the need to restrict in which situations the stdin is parsed into process.argv. E.g. Copy piped argument to process.argv only If the CLI command is one of {X,Y,Z}, otherwise ignore it.

For the 1st iteration, we can assume that the command can be read from process.argv[2].

Does not work with big content.

I started out using this package for getting a piped argument.
However, it doesn't seem to work with big content.
At that point I switched to get-stdin which does work with bigger content.