The date command is used to display and set the system date and time. It can also be used to print the time in different formats and calculate future and past dates. The date command has the following syntax:
date [option]... [+format]
The format controls begin with the % symbol and are substituted by their current values. For example, to display the current year, month, and day, we can use the following command:
date +"Year: %Y, Month: %m, Day: %d"
To set the system clock manually, we can use the --set or -s option followed by the date and time string. For example, to set the date and time to 5:30 PM, May 13, 2010, we can use the following command:
date --set="20100513 05:30"
The other tasks are not possible with the date command because:
Synchronize the hardware and system clocks: The date command cannot synchronize the hardware and system clocks. To do this, we need to use the hwclock command, which can read or set the hardware clock, and also synchronize it with the system clock.
Set the hardware clock: The date command cannot set the hardware clock. To do this, we need to use the hwclock command with the --systohc or -w option, which will copy the system time to the hardware clock.
Update the time via NTP: The date command cannot update the time via NTP (Network Time Protocol). To do this, we need to use the ntpdate command, which will query an NTP server and set the system clock accordingly.
References:
Date Command in Linux: How to Set, Change, Format and Display Date
date command in Linux with examples - GeeksforGeeks
Date Command in Linux | Linuxize
