systemctl : Control the systemd and service
[SYNOPSIS] systemctl OPTION COMMAND
COMMAND
start Start (activate) one or more units
ex. # systemctl start sshd.service
stop Stop (deactivate) one or more units
ex. # systemctl stop sshd.service
reload Reload one or more units
ex. # systemctl reload sshd.service
restart Start or restart one or more units
ex. # systemctl restart sshd.service
status Show runtime status of one or more units
ex. # systemctl status sshd.service
enable Enable one or more unit files
ex. # systemctl enable sshd.service
disable Disable one or more unit files
ex. # systemctl disable sshd.service
show Show properties of one or more
ex. # systemctl show sshd.service
cat Show files and drop-ins of specified units
ex. # systemctl cat sshd.service
edit Edit one or more unit files
ex. # systemctl edit sshd.service
list-dependencies Recursively show units which are required or wanted by the units or by which those units are required or wanted
ex. # systemctl edit sshd.service
get-default Get the name of the default target
set-default NAME Set the default target
ex. # systemctl set-default graphical.target

OPTION
-a Show all properties/all units currently in memory, including dead/empty ones. To list all units installed on the system, use 'list-unit-files' instead.
-t List units of a particular type
ex. # systemctl -t service