systemctl help

**1. start a service**

`sudo systemctl start nginx.service`

**2. Stop a service**

`sudo systemctl stop nginx.service`

**3.Restart a service**

`sudo systemctl restart nginx.service`

**4.Reload a service**
  
without interrupting the normal functionality
  
`sudo systemctl reload nginx.service`

**5. Enable a service at bootup**

`sudo systemctl enable nginx.service`

**6. Disable a service at bootup**

`sudo systemctl disable nginx.service`

**7. To get all of the unit files that systemd has listed as “active”**

`systemctl list-units`

**8. To list all of the units that systemd has loaded or attempted to load into memory, including those that are not currently active**

`systemctl list-units --all`

**9. To list all of the units installed on the system, including those that systemd has not tried to load into memory**

`systemctl list-unit-files`