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。
systemctl list-unit-files systemctl list-units systemctl list-unit-files | grep nfs
/lib/systemd/system/nfs-server.service /etc/systemd/system/
https://www.suse.com/support/kb/doc/?id=000019672