看了下/etc/hosts和/etc/hostname，似乎没问题
最后搜索到的结论是，hostname不要用localhost，所以这个systemd……嗯……就这样吧，毕竟自己菜不是（我用localhost当hostname碍Lennart什么事了！
用hostnamectl看了下，显示的是transient hostname，这个transient hostname，可以是dhcp之类的从网络上获取的
https://unix.stackexchange.com/question ... -at-reboot
My problem (and the way I ended up here) was that I had the hostname set as the default localhost and according to the hostnamectl man page:
This tool distinguishes three different hostnames: the high-level "pretty" hostname which might include all kinds of special characters (e.g. "Lennart's Laptop"), the static hostname which is used to initialize the kernel hostname at boot (e.g. "lennarts-laptop"), and the transient hostname which is a default received from network configuration. If a static hostname is set, and is valid (something other than localhost), then the transient hostname is not used.
So a solution would be not to have the hostname set as localhost
Another solution is to make your dhcp configuration in /etc/dhcp/dhclient.conf not to request for a hostname by removing the host-name (and perhaps the domain-name) from the request property