What is PM2?
PM2 (http://pm2.keymetrics.io/) is a command-line utility that simplifies many of the tasks associated with running Node applications, monitoring their status, and efficiently scaling them to meet increasing demand.
PM2 can be used to instrument deployment and monitoring of your Node processes, both via the command line and programmatically. PM2 spares the developer the complexity of configuring clustering boilerplate, handles restarts automatically, and provides advanced logging and monitoring tools out of the box.
Installation
Step 1 : PM2’s command-line utility, pm2, is available via npm.
sudo npm install -g pm2
Step 2 : Test PM2
pm2 --version
Working with Processes
Step 1 : Now, let’s create a simple Node application. When accessed, it does nothing more than display the message “Hello, world. ” to users.
mkdir my-app
cd my-app/
nano index.jsNext, copy and paste the following pieces of code in the index.js files
// my-app/index.js
var express = require('express');
var morgan = require('morgan');
var app = express();
app.use(morgan('combined'));
app.get('/', function(req, res, next) {
res.send('Hello, world.\n');
});
app.listen(8000);Install the project’s dependencies
npm install express morgan
Step 2 : In this example, we instruct PM2 to start our application by executing its index.js script.
pm2 start index.js --name my-app We also provide PM2 with an (optional) name for our application (my-app), making it easier for us to reference it at a later time.
Step 3 : We can verify this by calling our application’s sole route using the curl command-line utility
curl localhost:8000 
PM2 offers straightforward commands : list, show, stop, start, restart, delete
Step 4 : List all processes
pm2 list 
Step 5 : Describe all parameters of a process
pm2 show my-app 
pm2 restart my-app 
Step 7 : Stop a process
pm2 stop my-app 
Step 8 : stop and delete a process from pm2 process list
pm2 delete my-app 
