PM2 lets you run your nodejs scripts forever. In the event that your application crashes, PM2 will also restart it for you.
Install PM2 globally to manager your nodejs instances
npm install pm2 -g
Navigate to the directory in which your nodejs script resides and run the following command each time you want to start a nodejs instance to be monitored by pm2:
pm2 start server.js --name "app1"
List all nodejs instances managed by pm2
Stop a particular nodejs instance
pm2 stop <instance named>
Delete a particular nodejs instance
pm2 delete <instance name>
Restart a particular nodejs instance
pm2 restart <instance name>
Monitoring all nodejs instances
As opposed to restart, which kills and restarts the process, reload achieves a 0-second-downtime reload
pm2 reload <instance name>
pm2 logs <instance_name>