System administration command. Read or set the hardware clock. This command maintains change information in /etc/adjtime, which can be used to adjust the clock based on how much it drifts over time. hwclock replaces the clock command. The single-letter options are included for compatibility with the older command.
You may specify only one of the following options:
- -a, --adjust
Adjust the hardware clock based on information in /etc/adjtime and set the system clock to the new time.
Print the kernel’s hardware clock epoch value, then exit.
- -r, --show
Print the current time stored in the hardware clock.
- -s, --hctosys
Set the system time in accordance with the hardware clock.
- --setepoch, --epoch=year
Set the hardware clock’s epoch to year.
- --set --date=date
Set the hardware clock to the specified date, a string appropriate for use with the date command.
- -v, --version
Print version and exit.
- -w, --systohc
Set the hardware clock in accordance with the system time.
The following may be used with the above options:
Print information about what hwclock is doing.
The hardware clock is stored in local time.
Disable /etc/adjtime facilities.
Do not actually change anything. This is good for checking syntax.
- -u, --utc
The hardware clock is stored in Universal Coordinated Time.