Which command displays the current date, system time, hardware time, and time zone?

The command that displays the current date, system time, hardware time, and time zone is timedatectl. This utility is part of the systemd suite, and it provides a simple interface for checking and manipulating time and date settings on a Linux system.

When executed, timedatectl shows detailed information, including the current local time, UTC (Coordinated Universal Time), the time zone, the status of the NTP (Network Time Protocol) synchronization, and the hardware clock settings. This makes it a comprehensive tool for managing and viewing time-related information on the system.

In contrast, other options do not provide this level of detail or functionality. The command gettime is not a standard utility in Linux, and calendar typically refers to different functionalities, like displaying a calendar view rather than time settings. Dateinfo may lead one to think it provides date information, but it is not a standard or recognized command for such output in Linux. Therefore, timedatectl is the most accurate and relevant choice for obtaining time and date information on a Linux system.