21.sysetemctl-service-chkconfig服务管理

systemctl命令是系统服务管理器指令，它实际上将 service 和 chkconfig 这两个命令组合到一起。

任务	旧指令	新指令
使某服务自动启动	chkconfig –level 3 httpd on	systemctl enable httpd.service
使某服务不自动启动	chkconfig –level 3 httpd off	systemctl disable httpd.service
检查服务状态	service httpd status	systemctl status httpd.service（服务详细信息）systemctl is-active httpd.service （仅显示是否 Active)
显示所有已启动的服务	chkconfig –list	systemctl list-units –type=service
启动某服务	service httpd start	systemctl start httpd.service
停止某服务	service httpd stop	systemctl stop httpd.service
重启某服务	service httpd restart	systemctl restart httpd.service

1.启动nfs服务

systemctl start nfs-server.service 

2.设置开机自启动

systemctl enable nfs-server.service 

3.停止开机自启动

systemctl disable nfs-server.service

4.查看服务当前状态

systemctl status nfs-server.service 

5.重新启动某服务

systemctl restart nfs-server.service 

6.查看所有已启动的服务

systemctl list -units --type=service