How to setup pm2 to automatically start after reboot?

$ pm2 start
$ pm2 save
$ pm2 startup

You will see something like the following after you run the last command:

[PM2] Init System found: systemd
[PM2] To setup the Startup Script, copy/paste the following command:
sudo env PATH=$PATH:/usr/local/lib/nodejs/node-v12.18.0-linux-x64/bin /usr/local/lib/nodejs/node-v12.18.0-linux-x64/lib/node_modules/pm2/bin/pm2 startup systemd -u shukebeta --hp /home/shukebeta

copy the sudo line & paste it on your command line then press Enter! You have done.