Services there are the background run programs also called daemons.

sudo systemctl <command> <service name>

Modules control сommands

• start
• stop
• restart
• reload
• reload-or-restart
• enable (with --now flag – enable and run immediately)
• disable (with --now flag – disable and stop immediately)
• mask – mark service as completely unable to be run or enabled

Status and information commands

Check processes and services running by <user>
sudo ps -efl | grep '<user>'

• status
• list-units
• list-unit-file

Useful services

• nginx
• openssh
• systemd-timesyncd – leightweight NTP-client