systemctl - Query or send control commands to the systemd manager.
[SYNOPSIS] systemctl OPTIONS COMMAND
OPTIONS
--all Show all units/properties, including dead/empty ones
# systemctl --all
--t List only units of a particular type
# systemctl -t service

COMMAND
start Start (activate) one or more units
# systemctl start sendmail.service
stop Stop (deactivate) one or more units
# systemctl stop sendmail.service
reload Reload one or more units
# systemctl reload sendmail.service
restart Start or restart one or more units
# systemctl restart sendmail.service
status Show runtime status of one or more units
# systemctl status sendmail.service
enable Enable one or more unit files
# systemctl enable sendmail.service
disable Disable one or more unit files
# systemctl disable sendmail.service