Modify

Systemd (most modern distributions)

systemctl start [service_name]	Starts a stopped service.
systemctl stop [service_name]	Stops a running service.
systemctl restart [service_name]	Restarts a running service.
systemctl enable [service_name]	Enables a service to start automatically at boot.
systemctl disable [service_name]	Disables a service from starting automatically at boot.
systemctl reload [service_name]	Reloads the service configuration without restarting it (if supported).
systemctl mask [service_name]	Prevents a service from being started manually or automatically.
systemctl unmask [service_name]	Reverses the effect of mask, allowing the service to be started again.

SysV init (older distributions)

service [service_name] start	Start
service [service_name] stop	Stop
service [service_name] restart	Restart
service [service_name] reload	Reload
chkconfig [service_name] on	Enables a service at boot.
chkconfig [service_name] off	Disables a service from starting at boot.
update-rc.d [service_name] start <runlevels>	(SysV init) Enable service in specific runlevels at boot.
chkconfig [service_name] on/off	(SysV init) Enable/disable service for all runlevels.

Upstart (rarely used now)

start/stop/restart [service_name]	Service commands.
initctl start [service_name]	Starts a service.
initctl stop [service_name]	Stops a service.