[syslog-ng]How can I stop syslog-ng by command

Hello everyone: I have a simple question to ask you. Could you tell me a command to stop/start my syslog-ng server? In my Syslog-ng 1.6.5, I can't use "syslog-ng stop" to stop my syslog-ng. I can only use kill, but I don't think it is a good idea. Thx!!