The date command is used to display or set the system's date and time. The date command has the following syntax:
date [options] [+format] [time]
The options can modify the behavior of the date command, such as setting the time zone, printing the date in RFC 3339 format, or updating the hardware clock. The +format argument can specify the output format of the date command, using various conversion specifiers that represent different components of the date and time, such as %Y for the year, %m for the month, %d for the day, %H for the hour, %M for the minute, and %S for the second. The time argument can set the system's date and time, using the format MMDDhhmm[[CC]YY][.ss], where MM is the month, DD is the day, hh is the hour, mm is the minute, CC is the century, YY is the year, and ss is the second.
Therefore, the date command can accomplish the following tasks:
* A. Set the system's date and time. For example, to set the system's date and time to November 8, 2023,
18:30:00, the command would be:
date 110818302023.00
* E. Display time in a specific format. For example, to display the current date and time in the format YYYY-MM-DD HH:MM:SS, the command would be:
date +%Y-%m-%d %H:%M:%S
The other options in the question are not correct for this task. The date command cannot set the system's date but not the time, as the time argument requires both the dateand the time components. The date command cannot calculate the time span between two dates, as it can only display or set the current date and time. The date command cannot print a calendar for a month or a year, as that is the function of the cal command.
References:
* LPI 102-500 Exam Objectives, Topic 105.1: Customize and use the shell environment
* LPI 102-500 Study Guide, Chapter 5: Customizing Shell Environments, Section 5.1: Working with the Shell
* date man page