systemctl/service redhat6 redhat7区别

1	RHEL是什么缩写？
Red Hat Enterprise Linux
2	CentOS是什么缩写？
Community Enterprise Operating System，社区企业操作系统
3	RHEL与CentOS什么区别？
redhat是收费版，CentOS免费；
4	systemctl/service redhat6 redhat7区别
systemctl是rhel7引入的命令，对rhel6中的service、chkconfig命令进行了整合；
RHEL6                 RHEL7                      作用
service foo start   systemctl start foo.service  启动服务
service foo restart systemctl restart foo.service 重启服务
service foo stop   systemctl stop foo.service  停止服务 
service foo reload  systemctl reload foo.service 重新加载配置文件
service foo status  systemctl status foo.service  查看服务状态
chkconfig foo on   systemctl enable foo.service 开机自动启动
chkconfig foo off   systemctl disable foo.service 开机不自动启动
chkconfig foo      systemctl is-enabled foo.service 查看是否开机启动
chkconfig --list    systemctl list-unit-files --type=service 查看各个级别下服务的启动与禁用情况