hwclock
hwclock is an administration tool for the time clocks. It can display the Hardware Clock time and set the Hardware Clock.
Command Syntax
Under Linux bash, use the following format,
hwclock [function] [option...]
Parameter
Parameter | Description |
function: | |
-h, --help | Show help text and exit. |
-r, --show | Read hardware clock and print result. |
--set | Set the RTC to the time given with –date. |
-s, --hctosys | Set the system time from the hardware clock. |
-w, --systohc | Set the hardware clock from the current system time. |
--systz | Set the system time based on the current timezone. |
--adjust | Adjust the RTC to account for systematic drift since the clock was last set or adjusted. |
--getepoch | Print out the kernel's hardware clock epoch value. |
--setepoch | Set the kernel's hardware clock epoch value to the value given with –epoch. |
--predict | Predict RTC reading at time given with –date. |
-V, --version | Display version information and exit. |
option: | |
-u, --utc | The hardware clock is kept in UTC. |
--localtime | The hardware clock is kept in local time. |
-f, --rtc <file> | Special /dev/... file to use instead of default. |
--directisa | Access the ISA bus directly instead of /dev/rtc. |
--badyear | Ignore RTC's year because the BIOS is broken. |
--date <time> | Specifies the time to set the hardware clock to. |
--epoch <year> | Specifies the year which is the beginning of the hardware clock's epoch value. |
--noadjfile | Do not access /etc/adjtime; this requires the use of   either --utc or –localtime. |
--adjfile <file> | Specifies the path to the adjust file; the default is /etc/adjtime. |
--test | Do not update anything, just show what would happen. |
-D, --debug | Debugging mode. |
Example
- Â Show the help information of hwclock command.Â
admin@193:/$ hwclock -h Usage:  hwclock [function] [option...] Functions:  -h, --help          show this help text and exit  -r, --show          read hardware clock and print result     --set           set the RTC to the time given with --date  -s, --hctosys       set the system time from the hardware clock  -w, --systohc       set the hardware clock from the current system time     --systz         set the system time based on the current timezone     --adjust        adjust the RTC to account for systematic drift since                        the clock was last set or adjusted     --getepoch      print out the kernel's hardware clock epoch value     --setepoch      set the kernel's hardware clock epoch value to the                        value given with --epoch     --predict       predict RTC reading at time given with --date  -V, --version       display version information and exit Options:  -u, --utc           the hardware clock is kept in UTC     --localtime     the hardware clock is kept in local time  -f, --rtc <file>    special /dev/... file to use instead of default     --directisa     access the ISA bus directly instead of /dev/rtc     --badyear       ignore RTC's year because the BIOS is broken     --date <time>   specifies the time to which to set the hardware clock     --epoch <year>  specifies the year which is the beginning of the                        hardware clock's epoch value     --noadjfile     do not access /etc/adjtime; this requires the use of                        either --utc or --localtime     --adjfile <file> specifies the path to the adjust file;                        the default is /etc/adjtime     --test          do not update anything, just show what would happen  -D, --debug         debugging mode
- Â Display hardware clock time.
admin@193:/$ hwclock --show 2023-11-27 11:09:19.186623+00:00
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