Command line tool to extract values from a JSON file.

demo.sh

echo '{"foo1":123, "foo":{"bar":[1,2,3]}}' | ./json.js foo.bar.2

json.js

#!/usr/bin/env node

var keypath = process.argv[2];
var infile = process.argv[3];
if (infile) {

	var input = require(process.argv[3]);
	output(input);

} else {
	
	var stdin = process.stdin,
		inputChunks = [];

	stdin.resume();
	stdin.setEncoding('utf8');

	stdin.on('data', function (chunk) {

		inputChunks.push(chunk);
	});

	stdin.on('end', function () {

		var input = JSON.parse(inputChunks.join(''));
		output(input);
	});
}

function output(parsedInput) {

	var keys = keypath.split('.');
	var value = parsedInput;
	keys.forEach(function (key) {

		value = value[key];
	});

	console.log(JSON.stringify(value, null, "\t"));
}