Change Hostname Without Reboot

Generate commands to change a hostname without rebooting. Run the block that matches the machine.

• Ubuntu, Debian, RHEL, CentOS, Rocky, Alma 7 and later, Fedora, SUSE, Arch, and Amazon Linux use hostnamectl.
• RHEL 6 and CentOS 6 write /etc/sysconfig/network. Alpine writes /etc/hostname.
• macOS uses scutil. FreeBSD uses sysrc. Windows uses Rename-Computer.

Each Linux block also adds the name to /etc/hosts. A cloud image can put the old name back on the next boot unless preserve_hostname is true.