A.使用命令systemctlB.使用命令systemctl get-default可以查看C.使用命令systemctl get-level可以查看D.使用命令systemctl set-default可以查看
A.systemctl enable httpd.serviceB.systemctl disable httpd.serviceC.systemctl start httpd.serviceD.systemctl status httpd.service
A.crontab -lB.crontab -eC.crontab -e abcD.crontab -r