Linux Hostname

External

• http://man7.org/linux/man-pages/man1/hostname.1.html

Internal

• Linux Network Concepts

Overview

There are three different hostnames:

• The high-level "pretty" hostname which might include special characters.
• The static hostname which is used to initialize the kernel hostname at boot.
• 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.

The static and transient hostnames are limited to the usually accepted characters of Internet domain names.

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.

The hostname can be set at runtime with at least two commands: hostname and hostnamectl. The hostname command shows or set the system's host name. Note that the name set is such a way is ephemeral - will disappear at reboot. There's also a daemon that reacts to network events and sets the hostname: systemd-hostnamed. To permanently set name, configure the appropriate file. See below.

Host Name and the Domain Name

When a machine is initially configured, the installation program usually suggest a fully qualified host name that usually has a host name component and a domain name component.

Finish this.

Getting the Hostname

Display the hostname:

hostname

Display the fully qualified domain name (the long host name):

hostname -f

Display the DNS domain:

hostname -d

/etc/hostname

The /etc/hostname file configures the name of the local system that is set during boot using the sethostname(2) system call. It should contain a single newline-terminated hostname string. Depending on the operating system, other configuration files might be checked for configuration of the hostname as well, however only as fallback.

You may use hostnamectl to change the value of this file from the command line. Also see systemd-hostnamed /etc/hostname.

/proc/sys/kernel/hostname

cat /proc/sys/kernel/hostname

Configuration

Configuring the Machine Name