centos7 上在主機名變更新增了一個hostnamectl 指令 ，該指令的無論在輸出和更改上都較之前更加的便利。先看下hostname的help幫助信息：

從上面的help 幫助里可以看到，在設置主機名時，這里涉及到四種主機名，在hostnamectl 的man手冊里給予了說明和解釋，如下：

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 might be
assigned temporarily due to network configuration and might revert back to the static hostname if network connectivity is lost and is only temporarily
written to the kernel hostname (e.g. "dhcp-47-11").
Note that the pretty hostname has little restrictions on the characters used, while the static and transient hostnames are limited to the usually accepted
characters of Internet domain names.
更改主機名

一般情況下都是使用set-hostname進行更改：

The static hostname is stored in /etc/hostname, see hostname(5) for more information. The pretty hostname, chassis type, and icon name are stored in /etc/machine-info, see machine-id(5).
set-icon-name 設置的主機一般和圖形界面會用到，對應的hostnamectl 輸出中的Icon name  ，set-chassis 指定了主機的平臺類型，如本機的是desktop，還可以設置為："desktop", "laptop", "server", "tablet", "handset"