/usr/bin/sg_sat_datetime

Usage: sg_sat_datetime [--dma] [--elapsed] [--format] [--help] [--hex]
                       [--milliseconds=MS] [--readonly] [--seconds=SECS]
                       [--srep] [--verbose] [--version] DEVICE
  where:
    --dma|-d           use DMA to read date and time from log
    --elapsed|-e       show time as '<n> days hh:mm:ss.xxx' where
                       '.xxx' is the remainder milliseconds. Don't show
                       '<n> days' if <n> is 0 (unless '-e' given twice)
    --format|-f        output formatted date and time using
                       the default locale setting
    --help|-h          print out usage message, use twice for examples
    --hex|-H           output date and time in ASCII hexadecimal
    --milliseconds=MS|-m MS  set date and time to MS milliseconds since
                             1970-01-01 00:00:00 UTC
    --seconds=SECS|-s SECS   set date and time to SECS seconds since
                             1970-01-01 00:00:00 UTC
    --srep|-S          output date and time in seconds (def:
                       milliseconds)
    --verbose|-v       increase verbosity
    --version|-V       print version string and exit

Performs the ATA SET DATE TIME EXT command to set the device time if either
the --milliseconds=MS or --seconds=SECS option is given.  If --seconds
or --milliseconds options are not provided, the READ LOG EXT or READ LOG
DMA EXT command is issued to read the current date and time from device
statisics log address (04h) general statistics log page (01h). If the date
and time has not been set, the ATA DEVICE returns the the number of
milliseconds of power-on hours. The date and time value is based on
1970-01-01 00:00:00 UTC which also happens to be the time 'epoch'
of Unix machines.

Use '-hh' (the '-h' option twice) for examples.