linux上启动服务
1.apache
/etc/rc.d/init.d/httpd restart
(配置文件：/etc/httpd/conf/httpd.conf)
2.mysql
/etc/rc.d/init.d/mysqld restart  (#mysqladminshutdown)
(配置文件：/etc/my.cnf)
3.cron
/etc/rc.d/init.d/crond restart
(配置文件：/etc/crontab)
/var/spool/cron/
crontab -e