node-red/nodes/storage/28-tail.js

/**
 * Copyright 2013 IBM Corp.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 **/

var RED = require("../../red/red");
var fs = require("fs");
var spawn = require('child_process').spawn;

function TailNode(n) {
	RED.nodes.createNode(this,n);

	this.filename = n.filename;
	this.split = n.split;
	var node = this;

	var tail = spawn("tail", ["-f", this.filename]);
	tail.stdout.on("data", function (data) {
		var msg = {topic:node.filename};
		if (node.split) {
			var strings = data.toString().split("\n");
			for (s in strings) {
				if (strings[s] != "") {
					msg.payload = strings[s];
					node.send(msg);
				}
			}
		}
		else {
			msg.payload = data.toString();
			node.send(msg);
		}
	});
}

RED.nodes.registerType("tail",TailNode);