What does the `hostname` command do?

The hostname command is specifically designed to display or modify the system's host name. The host name is the label assigned to a device on a network, which is used to identify it uniquely among other devices.

When executed without any arguments, the hostname command outputs the current host name of the system. If a new host name is provided as an argument, the command will change the system's host name to the specified value, although this change may not persist after a reboot unless additional configuration is made in the system settings.

The other options do not accurately describe the functionality of the hostname command. For instance, displaying the current user, altering network settings, and controlling the system clock involve different commands and subsystems within Linux. The primary and distinct role of the hostname command is to manage the system's identification on a network, making it an essential tool for network configuration and management.