apachectl 调用 $httpd -k

1. kill - TERM `cat /usr/local/apache/logs/http.pid`

2. /bin/httpd -k  stop/start/restart/graceful/graceful-stop

3. apachectl -k stop

 发送停止信号给parent， 然后kill off its children, 花几秒时间

4. apachectl  -k graceful

parent advis children to exit or exit immediatly if they're not serving anyting

5 apachectl -k restart

kill all of chidren