Systemd

  
 vim /etc/systemd/system/foo.service
chmod +x /etc/systemd/system/foo.service 
 [Unit] Description=foo [Service] ExecStart=/bin/bash echo "Hello World!" [Install] WantedBy=multi-user.target 
 systemctl daemon-reload 
 systemctl start foo 
 You can also use systemctl cat nginx.service to simply view how the init script starts the service 
 To enable and start a service in the same line you can do 
 systemctl enable --now foo.service 
 To check if service is enabled 
 systemctl is-enabled foo.service; echo $? 
 To check the services that start with the OS in order you can do 
 systemctl list-units --type=target 
 
 Journalctl 
 List failed services 
 systemctl --failed 
 journalctl -p 3 -xb 
 To filter only 1 service you will need to use the flag -u 
 journalctl -u nginx.service 
 To have live logs on a service you can do 
 journalctl -f _SYSTEMD_UNIT=nginx.service 
 To have live-tail logs for 2 services example nginx and ssh 
 journalctl -f _SYSTEMD_UNIT=nginx.service + _SYSTEMD_UNIT=sshd.service 
 To check logs since the latest boot: 
 journalctl -b 
 To get the data from yesterday 
 journalctl --since yesterday
#or
journalctl -u nginx.service --since yesterday 
 To view kernel messages 
 journalctl -k