A Compact Guide That Explains PM2 Feature

PM2 is a Node process manager, Which is widely used in producation environment, And it is an open-source Node process manager. Used by many developers around the World.

With just a one line command and your server is alive for forever, And it will auto-restart also when it shutdown by some error. All the running process are managed by PM2. You can view each running process and there log by there process id, And can perfrom action on a paticular process by their process id. PM2 also sacle your applicaiton by serveral child process creating for though have the same server port. You can also see the CPU usage, memory used request and many more thins in that. It will manage most of the thing of server.

It will solve many problems few are:
1) It will restart the application if it is crashes.
2) It will help you by restarting your node application as a service every time you restart a server. There are many ways to do this, but pm2 makes it easier, and it has some added flexibility.
3) It will keep a log for your unhandled exception - in that case, in a file at /home/safeuser/.pm2/logs/app-err.log.

Command to install PM2: 

sudo   npm  install pm2 -g

Command to start PM2:

pm2 start <name_of_the_main_file>

Exapmle:

pm2 start app.js

Command to run your application as a service:

sudo  env PATH=$PATH:/usr/local/bin pm2 startup -u  safeuser

Please note, you can't use safeuser as a user name - use a name that correspond to your setup. 

Command to Monitoring all process launched:

pm2  monit

Command to list all process:

pm2 list

To stop PM2:

pm2 stop 0             # Stop specific process id

To restart PM2:

pm2 restart 0          # Restart specific process id

To remove process from pm2 list:

pm2 delete 0           # Will remove  process  from  pm2  list by id
pm2 delete all         # Will remove all processes from  pm2  list